|“||Flame of apocalypse that burns away everything in this world! Ride the Vanguard! Dragonic Overlord!||”|
—Toshiki Kai, Whenever he rides Dragonic Overlord.
Toshiki Kai is the deuteragonist in the anime and manga. During Season 4, he becomes the main protagonist after Aichi's disappearance. He is also the main protagonist of Neon Messiah, along with Aichi. He is a very serious character. It is known from the end of episode 1 that he had previously met Aichi and gave him the card Blaster Blade, which later becomes the heart of Aichi's Royal Paladin deck. His Vanguard Circle color is red.
Despite continuous reference to 'Kai' both in-series and out, Kai's given name is in fact Toshiki. Going with Japanese rules of etiquette, none of the characters in Vanguard refer to Kai by his given name because none of them are close enough to him socially to speak to him as such, much like how Mr. Mark only refers to Aichi as Sendou, and Katsumi Morikawa refers to Kamui as Katsuragi.
Kai is a serious person and doesn't like to joke around like other people his age. He doesn't talk much or to anyone. When cardfighting, he is shown to be more serious and confident on winning the game without any need of support. Despite his selectively mute personality, he has a best friend, who is Taishi Miwa.
There is also some speculation and various scenes in the anime that suggest Kai might have a soft spot for Aichi, even though he refuses to admit it. Often times, his friend Miwa will tease him about it. According to Miwa, Kai used to be more friendly before he moved away.
Kai is shown to have some knowledge when it comes to cooking and especially like onions. Whether this stems from him living alone and having to fend for himself remains to be seen.
He shares the popular phrase, "Final Turn!" with Ren Suzugamori, though Aichi recently adopted it as well as he got corrupted by PSY Qualia. This probably came from the fact that Ren and Kai were once on the same team.
After the VF Circuit, Kai adopts friendly personality towards Miwa and the rest of his friends at Card Capital, which he goes to a lot now, but still retains his seriousness and confidence. He is shown to be more supportive and helpful with his school's Cardfight Club; he loaned Morikawa his old Kagero deck and helped Izaki train for the High School Vanguard Championships, showing he now tolerates the two. This extends outside of the club, shown with Aichi when he gives him advice, and Naoki after their fight. However, while watching how Aichi was able to defeat his old Kagero deck, and his match against Ren, he starts to feel inferior after witnessing how much their skills have grown, lamenting that he would probably lose if he fought them as he is currently.
After he became Reversed, Kai becomes obsessed with challenging strong fighters so Link Joker will become stronger. When facing such a fighter, for example Kenji, Kai will remark on that strength, saying that it is what he has been looking for.
His manga counterpart personality differs from his anime counterpart. He still is very much a serious person and is quite confident of him winning cardfight battles. Although he retains his seriousness, he actually enjoys going to Card Capital and smiles quite often. He seems more friendly and supportive towards Aichi. Also, he appears to talk more towards Miwa.
In Episode 162, however, Kai shows a different side to him. Horrified by what he's done, Kai challenges Aichi and reveals that what he's done hasn't caused anyone any happiness, and attempts to go into self-exile to amend for his crimes.
In Season 4, he starts to open up more and becomes friendlier than he was in the previous seasons. He also considers to keep his mates out of danger that shows he cares about his friends (Mates).
In the G series, he is more friendly and he doesn't seem to be as serious as he is seen smiling more. However, it seems he still secretly blames himself for the Link Joker incident, as he decided to follow Noa Hoshizaki, after learning from Nome Tatsunagi that he was possessed by Star-vader, Chaos Breaker Dragon.
Despite not having PSY Qualia himself, Kai possesses a few abilities reminiscent of said power. The most notable is his bond with Dragonic Overlord, which throughout the series has evolved to match Kai's feelings. When he was searching for the power to beat Ren, it evolved into Dragonic Overlord the End. When Kai was Reversed, it evolved into Dragonic Overlord "The Яe-birth". When he learned the value of mates, it evolved into Perdition Emperor Dragon, Dragonic Overlord the Great. Also, he was able to see Brandt.
He is consistently touted as being the best player in terms of raw ability, and his name quickly becomes well known throughout the world.
He also demonstrates an incredible ease mastering new units, an ability showcased numerous times in season 1. On several occasions, he nearly completely rebuilds his deck once new cards are released, but plays them effectively and effortlessly as though he'd been using them his whole life. He is the first to show off Superior Riding, the Megablast technique, Crossriding, the Persona Blast technique, Limit Break, Ultimate Break, and Legion (technically however, due to the English anime not dubbing Season 4, that makes Ibuki the first to display Legion in English specifically, though Kai does use Legion later on).
It is worth noting that Kai acknowledges a similar ability in Ren, but Ren's seems to be more based off an intuition for how cards work together than Kai's more experience based skill.
Kai was first seen in the local card shop, cardfighting with Katsumi Morikawa and beat him easily as he rode his trump card, Dragonic Overlord. Then Morikawa requested a rematch, at first Kai rejected it, reasoning that he was not strong enough but accepted when he bet a card which attracted his attention, Blaster Blade, a card he stole from Aichi. Kai disposed of him easily and took the card, then Aichi came and challenge him to claim back his card. Kai accepted the challenge and teaches him the rules because Aichi was a beginner in Cardfight!! Vanguard. Before the cardfight starts, Kai returns the card to Aichi, hoping that he will use it effectively against him. Throughout the fight, Aichi learns that Kai was the one who gave the card to him during his childhood. Eventually, Kai loses the game and returns the card to Aichi, though he purposely held back during the fight.
Kai was seen again when Aichi and his friends spotted him walking back to his home. They decided to follow him secretly due to their curiosity, but Kai figures out they were tailing him. Aichi apologizes and asks him for another battle, but he declines it. However, when Kamui Katsuragi challenges him, he accepts it with an askance look. The next day, the two commence their fight. At first, Kai took the upper hand by riding a Grade 3 card very quickly, but shortly afterwards, Kamui countered it with his own Grade 3 card. However, Kai once again proved that he was the strongest as he rode Vortex Dragon, proceeding to activate its Mega Blast to retire the rear-guard units controlled by Kamui, leaving Kamui defenseless for the final attack from Kai. He left the scene after he defeated Kamui, but not before Aichi told him he vowed to become a stronger and more worthy opponent in order to challenge Kai again.
After that, he entered the Local Shop Tournament, with a hope that he would find some strong opponent. However, he easily reached the Semi-Final in the tournament. After the setup of the Semi-Final round, he was selected to be the next opponent of Misaki. Kai announced "Final Turn" before he easily claimed victory against Misaki. During the final round, he once again defeated Kamui effortlessly and took the champion title. After the tournament, he was invited into the Regional Tournament with Kamui, Misaki and Aichi as a team, called Team Q4, short for Team Quadrifoglio.
In the First Round of the Regional Tournament, he annihilates his opponent without even breaking a sweat. Team Q4 easily won the second and third round. During the Finals of the Regional Tournament, he has a close fight against Kaoru but stills wins the cardfight with two critical triggers. However, it was shown that Kai purposely let his opponent take the lead before crushing him, hoping to motivate Aichi's will to fight.
After the first Regional championship, Kai starts suspecting that Aichi might have the same ability as Ren. During Aichi's fight with Kyou, Kai confirmed it. Kai, not wanting to suffer what happened with Ren again, told Aichi that he is not getting stronger, but weaker, and quits Team Q4. He also appears to blame himself for this and for the currently unknown incident that happened with Ren, as shown by how after quitting Team Q4 he said "he made the same mistake again."
Kai later fought against Kourin Tatsunagi, who was looking for him and suspected he also had PSY Qualia, but confirmed that he didn't. Kai also said it is his fault that Aichi obtained PSY Qualia, and that he wants to exceed it. Then he accepted to help stop Aichi before he fully becomes like Ren.
Kai cardfights Aichi and talks about his past, how Aichi showed him that Vanguard fights are supposed to be fun and not all about power, later convincing him to abandon using PSY Qualia that true strength does not comes from that power but oneself.
Before the final match of the nationals, he challenges Ren for a fight in order to bring his former self back. Kai draws the card that will be the trump card to beat Ren and crossrides Dragonic Overlord the End saying that he will bring Ren back with this card. But Ren crossrides Phantom Blaster Overlord and wins. Later, he is seen in the match between Aichi vs Ren, where he helps Aichi snap out of PSY Qualia's influence. After the match, he gives Ren and Aichi a smile and thanks Aichi for saving Ren. At the end of the season, Kai finally challenges Aichi to a proper cardfight.
Kai is first shown fighting against Takuto Tatsunagi, who was using a Gold Paladin deck. Towards the end of the fight, Takuto rides Great Silver Wolf, Garmore, which transforms Kai's Kagero deck into a Narukami deck. The next day, Kai spots Aichi in the park and challenges him to a fight and during the battle, Kai does reveal he believes Aichi's story and starts to have certain memory flashes of Aichi's Blaster Blade.
Kai starts training to become stronger and fights Kyou on a mountain, winning the fight and triggering an avalanche, which Kai saves Kyou from.
During the Seoul Stage, he is seen with Ren and Asaka in his new team, Team New Asteroid, who wins all of their battles against Team Movie Stars in the first round of the Seoul Stage. He fights Kamui in the next match-up against Team Q4, winning the match by taking advantage of the special rule, using Dragonic Kaiser Vermillion's Limit Break twice in the match. He appears beside Tetsu after the match, watching Ren's and Asaka's match. Kai does not have any recollection of PSY Qualia as he did not react when Ren says that the power is incredible. In the final round of the Seoul Stage, he wins the match against Team Caesar's Gai Usui.
Team New Asteroid is invited to a summer resort island to train by the Tatsunagi Financial Group. He watches Aichi and his friends training on the beach. He paired up with Aichi for the Test of Courage and tells him that their paths will cross. Next morning, Kai is asked by Ren to play beach volleyball with him and Asaka, but declines, and asked Miwa out to cardfight with him. Later in the afternoon, he sees Q4 off from land as they go back to Japan, in preparation for the next stage.
Kai and the rest of the winners of each stage gather in Japan, the last stage of the VF Circuit. New Asteroid wanders around the amusement park where the final stage is held. After the winning ceremony, all the teams gather in a room that has a portal that creates a space connected between Cray and Earth to fight a mysterious empty power, Void. New Asteroid gets separated from the other teams by Leon Soryu not long after their arrival in the space. Ren uses his PSY Qualia to track Leon's whereabouts. After finding Leon, Kai challenges Leon and expresses his anger about "sacrificing" the three clans to bring back Aqua Force. He crossrides Dragonic Kaiser Vermillion "THE BLOOD" to counter Leon's Aqua Force units, but Leon managed to survive and crossrides Blue Storm Supreme Dragon, Glory Maelstrom and takes the win. Kai and his team were sent back to Earth as defeated cardfighters cannot exist in that space.
He is now a Second-year student at his high school and is a part of his school's cardfight club. He is seen briefly in episode 107, battling a kid in Card Capital.
During the intermural fight against Aichi's school, he is matched up against Naoki Ishida. He acknowledges his skill in Vanguard as Naoki pushes Kai to 5 damage. However, Kai manages to win the match with Eradicator, Dragonic Descendant and agreed to fight Naoki again. Later in the matchup, he swapped Morikawa's deck with his old Kagero deck. Through that cardfight, he sees Aichi grow even stronger as a player, commenting that even Dragonic Overlord The End could not reach him anymore.
During the tournament, he fights against Shingo crushing him completely commenting that he wanted to fight Aichi instead. But after his team fails to advance and after watching Ren and Aichi's Cardfight, Kai soon realizes that their skills have grown to the point where not even he can reach them anymore. He is later seen in Episode 126: The Mystery Dragon, where he witnesses a Reversed Naoki Ishida cardfight Aichi. After the fight, Kai picks up the mysterious card Eradicator, Vowing Saber Dragon "Яeverse" which burns right before his very eyes. He then confronts Takuto Tatsunagi about "Reverse," and ends up cardfighting Takuto's other side, who uses the Link Joker clan in an attempt to Reverse him. Tempting Kai with the power of Link Joker, the agent of Void, he accepts the power of Reverse and becomes a catalyst of what is to come.
The next day, he goes to see Ren to fight him, only to be told by Tetsu that he is not there, so, as an alternative, he decides to fight Tetsu instead with his new power, which Tetsu assumes is a new Narukami unit (as no one other than Takuto and Kai know about Link Joker at the time). He defeats and Reverses Tetsu Shinjou, and walks out Fukuhara High saying he hasn't mastered Link Joker yet. In his quest to master the Link Joker deck, he decides to leave the country running into Kenji Mitsusada, defeating and Reversing him as an unexpected bonus. He is later seen on a plane that is heading towards New York in America, possibly looking for stronger fighters. But it was later revealed that Kai went to New York to reverse countless of cardfighters around the world.
In episode 147, after Kai returned to Japan, Takuto's secretary was sent to drive Kai to meet Takuto but his journey was intercepted by Miwa who sought answers from Kai. Kai managed to reverse Miwa, revealing that he became a reversed fighter by his own will to be able to fight Aichi and Ren as their equal. He is later seen observing a fight between Miwa and Misaki on top of a building. After witnessing Miwa's loss against Misaki, he now gets into a cardfight with Aichi, saying how he has waited for this moment. He confidently wins the fight, entering the building satisfied with what he had accomplished.
After Aichi and Ren storm the Tatsunagi building, Takuto has Kai fight Ren, a match both have been looking forward to since their fight from Season 1, with Kai finally understanding why Ren would ever be tempted by such a power like PSY Qualia due to his experience with the Link Joker power. Ren revealed his new crossbreak ride, Revenger, Dragruler Phantom in an attempt to win on final turn. However, Kai manages to hold out and reveals his newest ace card, Dragonic Overlord "The Яe-birth", a Reverse unit that even Takuto did not know existed, and manages to attack him up to three times, the final attack ending on a triple critical. Both knew from the start that Ren could not heal enough times to save himself but continued to damage check anyway because of how much they both enjoyed their cardfight managing to heal twice before submitting. With this victory, Kai became truly satisfied as when Takuto ordered Kai to fight Aichi, he refused because he already defeated him before and thus sidelines himself to observe Aichi and Takuto's fight. After Aichi and Takuto's fight, Kai appears in front of Aichi still reversed saying that he was the opponent he was looking for and challenged him to a cardfight.
Kai states that he is in the middle of being un-Reversed and declares that, at his strongest, he wants to face Aichi at his strongest before he becomes completely un-Reversed and loses his deck. He tells Aichi that not only did he accept Link Joker, but its power never truly took control of him and knew exactly what he was doing. Knowing that, he declares that this will be his last fight against Aichi as he will disappear from his life due to the things he did when he was Reversed. Aichi says that he shouldn't disappear from their lives as Kai had become an example of what he should strive for as a cardfighter. They symbolize this by riding Blaster Blade and Dragonic Overlord, units that have become synonymous with each respective cardfighter. As he tries to overpower Aichi, Aichi manages to hold out his defenses. He finishes the fight with Liberator, Monarch Sanctuary Alfred which superior calls the field including Blaster Blade Liberator which finishes him off. As he is unreversed, Kai understands that by shutting everyone away, he doesn't become stronger but through friends and rivals, one can become stronger and stronger while at the same time raising everyone's strength around them. With this in mind, he has a new plan to get stronger, together with his best friend Aichi.
A while after the end of Link Joker's failed invasion, Kai headed over to Card Capital to see Aichi only for Shin to wonder who he is. Upon asking Emi and later Misaki, they both say that they do not know Aichi and he realizes that something is wrong. Upon entering the Physics room where Aichi would hold his Cardfight club, he is given a Royal Paladin deck with Blaster Blade Seeker. He encounters Naoki who was curious about Kai having forgotten about Aichi as well. He challenges him to a cardfight as he notices that Naoki is getting a reaction upon seeing the deck. Upon riding Blaster Blade, Naoki finally remembers Aichi as they vow to find him. He then challenges Misaki as she got a reaction from seeing Blaster Blade and hopes to trigger that memory with a cardfight. As they fight, Kai attempts to drop subtle hints towards her past when she was using Oracle Think Tank. At the end of the fight, Kai demonstrates Seeker, Sacred Wingal's ability to Legion with Blaster Blade Seeker finally unlocking Misaki's memories of Aichi. Seeing as how these effects triggered both Naoki and Misaki's memories of Aichi, Kai now sees a way to gain allies in search of the missing Aichi.
He seeks Ren as a potential mate but after showing him Blaster Blade, it doesn't trigger any hidden memories and Kai gives up for now. During Kai and Miwa's club meeting (which Morikawa and Izaki are not a part of), he challenges Miwa by giving him his Kagerō deck and engage in a match similar to Kai and Aichi's first cardfight. Upon riding Seeker, Thing Saver Dragon and using Blaster Blade to Legion with it, he unlocks Miwa's memories of Aichi.
Upon seeing Ultra Rare on the television, Kai remembers Aichi telling him of a cardshop called Psy that the idol group runs. Hoping to find clues about Aichi's and Kourin's disappearance. Kourin's, he goes there. However, instead of finding what he was looking for, he met a mysterious young man named Olivier Gaillard who introduced himself as a Quatre Knight. Gaillard tells Kai to forget about looking for Aichi, but the latter refuses. They engaged in a match with Gaillard triumphing in the end. Kai suffers judgement after he had lost, which is going through a fire the burns away the person's fighting will, from the result of the Holy Prominence Prison. Galliard then warns Kai that there are other Quatre Knights besides him and that they will destroy anyone that gets in the way, including Kai's mates. Gaillard disappears in a blaze of blue fire afterwards, leaving Kai flat on the ground, agonizing over the situation at hand. He struggles to get to the others in time as he catches up to Ishida after facing judgement and together finds Miwa in the same way realizing that this may be an enemy they are not ready for. Upon realizing that the Quatre Knights are just going to keep going after Kai's group, he decides to abandon his mates and go after Aichi alone. But Kamui, not wanting Kai to act alone anymore, defeats him in a cardfight saying that as his mates, they are willing to go into these dangerous situations knowing the consequences. Kai relents and accepts the group's help in the end. Then, as Misaki and Kamui are at the airport, he challenges Ren to fight him and learn everything he knows. He defeats him and reveals a stone circle formation which lead them to a portal area which they are greeted by Gaillard who defeats Naoki easily. As Kai gets ready to fight, they are surprised by an appearance by Kourin who allies herself not only with the Quatre Knights, but now uses the Link Joker clan. During their fight, Kai is shown an image of Aichi who tells them to forget about him and leave. While the others believe they are being tricked, Kai acknowledges that this is the real Aichi as his words burn deep as he loses to Kourin. While undergoing Judgement, Kourin takes Blaster Blade Seeker to give back to Aichi as the portals are destroyed.
Needing to train, everyone decided to visit Leon Soryu's island. While there, Kai watched Leon defeat Naoki four times before Leon decided to fight Kai to figure out his thoughts. Kai loses, and Leon does not detect any wind behind his actions; meaning Kai seemed to be lacking something important. Miwa then tossed a Kagerō deck to him and Kai realized that if he wanted to get Aichi back, Kai had to be true to himself, which included going back to his Kagerōs.
After Naoki found the entrance to their base, they storm it in hopes of defeating the Quatre Knights, but under the risk that if they lost, their memories of Aichi would be purged as well. Undaunted, Kai continued on until he reached Gaillard after the latter had defeated Kamui. He then challenged Gaillard and defeated him with his new Legion Perdition Dragon, Vortex Dragonewt, with his flames overwhelming Gaillard's. However, after defeating him, Kai, Gaillard and Naoki are all trapped in Raul Serra's ice prison, with Gaillard's flames being too weak to melt the ice after receiving Kai's Judgement. With the help of Leon and Ren, they manage to escape. After witnessing Gaillard defeat Raul and enacting Memory Judgement upon him, Kai and Gaillard fought once more with Kai unveiling his reborn avatar Perdition Emperor Dragon, Dragonic Overlord the Great and overwhelming Gaillard in a heated battle.
He then set his sights upon Aichi who revealed his corrupted avatar, Star-vader, Blaster Joker and asked that if Kai loses, he will become a Quatre Knight, which he agreed to. During the fight Kai kept trying to convince Aichi not to isolate himself from his mates, but Aichi didn't listen and rode his avatar, Blaster Joker. He then performed Legion with Kourin's avatar Photon, and demonstrated his Legion's ability, Absolute Lock, which locked all of Kai's rear-guards and retired his Legion Mate, Neo-Flame. Kai was astounded by this ability but did not waver, riding Overlord again and performing Legion once more. He tried to win that turn, but Aichi stopped his second Legion attack. Aichi used Absolute Lock once more, retiring Neo-Flame and locking Kai's units. Kai sensed the good part within Blaster Joker then and blocked the attack. He then made use of Aichi's thoughts against him, which lead Aichi to be conflicted about what he had done. Kai then asked if anyone was willing to take Aichi's burden, with everybody agreeing, much to his opponent's surprise. To prove Aichi that everybody will save him from his fate, Kai declared Final Turn and rode Overlord for the third time, performing Legion once more. Ren noted that Kai was "milking" Legion, but Leon said that it was showing his bond with his mates. Kai had Overlord attack Imaginary Plane Dragon, pulling a Double Critical drive check. He then stood his Legion and attacked Aichi's Legion. Aichi guarded, but Kai pulled another Double Critical drive check, breaking through with 5 Critical and leaving Aichi with no chance of recovering, thus winning the game.
After the fight, the Seed of Link Joker attacked Kai but Kai called out to Blaster Blade. Blaster Joker then returned to normal, cutting through the Seed. Then all of Aichi's friends appeared as the avatar of Blaster Blade, breaking the Seed into fragments, which entered everyone who witnessed the fight. Blaster Blade then said that the Seed will now enter fighters who know forgiveness, saying that one day Link Joker will be accepted by Cray as a new Clan instead of an invader. He then envisions himself sparing with Blaster Dark and Blaster Joker.
The next day after the incident, Kai waits for Aichi at Cardfight Capital after defeating Miwa several times. Once Aichi comes, he then challenges Aichi to a cardfight.
In Episode 195, a year later, he was mentioned that several pro collage and leagues were planning on recruiting him but he has not made any plans yet until he appeared at the end meeting Aichi and Naoki at the place the former two first met.
In episode 196, after the graduation ceremony he was finally more interactive with others as he sighed an autograph for a girl who asked for it. At the tournament he was shocked to see Ren wearing his trench coat again and mentioned during his fight with him that he "hated" that Ren's look. In the final round, he was about to fight Aichi as he mentioned that he will be going to Europe to fight and train with Gaillard and wouldn't be able to fight with him for a while but Aichi assured him as long as they play the game they will fight each other again as they both open up their vanguards.
G Season 2
Kai makes a reappearance in Cardfight!! Vanguard G: GIRS Crisis for the G Quests. He is first seen looking at Ibuki's message in what looks like Paris. The next day, when Kiba's corporation being completely taken over is in the newspaper, Kai is seen again when he is greeted by Kouji Ibuki.
Later Kai is seen again at Dragon Empire Branch fighting Mamoru Anjou, with the latter being defeated and then fighting the branch chief afterwards. Later, he is introduced by Kamui to TRY3 along with Miwa, Naoki and Shingo. On that same night Kai encountered a washed-up Shion who fell to his knees after his last coin fell into the drain at a vending machine near a self-service laundry. Kai then bought black coffee for him and Shion. Afterwards, they both cardfight for more than 10 times with Shion being defeated every time. Kai then covered Shion, who had fallen asleep, with his black jacket that he wore in Season 2. The next day, Kai was announced as the Super Chaser for Dragon Empire G Quest and those who beat him would gain 10000 points. Kai was later seen watching Shion and Miwa fight in order to release Chrono and Tokoha. Miwa then hints that Kai and Ibuki are the 'bad guys' in Star Gate. That night, Kai, Miwa and Ibuki were having dinner on a boat while discussing about TRY3 and how Shion wants to become stronger.
Later Kai is seen again as one of the bosses of the Star Gate Branch G Quest along with Ibuki. He was then challenged by Shion and faced with his Narukami deck. After seeing how strong Shion's image, he then beats him and tells him that he's willing to fight him anytime. After the match, he tells Ibuki that Team TRY3 may surpassed his expectation from them.
During the final leg of the G Quests, it is revealed that Team TRY3 would have to battle against Kai's team, Team Q4, in a final exhibition battle. For them however, it was an opportunity to test TRY3's team and see if they would be good enough to handle the final stages of their plan to end Ryuzu Myoujin's plans. Kai battled against his 'protege,' Shion Kiba, and commented on how far he's come since their repeated fights in the past. To show respect to this, Kai battled using his Kagero Deck focused on Dragonic Overlord The Legend. Despite Kai's tactics and raw power, Shion turned the tables and commented on a fight well done.
After the fight, he waited and prepared to act with his allies to overload the Stride Gate to find Ryuzu's hideout. Once the Stride Gate overloaded, he summoned Dragonic Overlord to continue pumping Stride Energy and together with his friends, found Ryuzu's base of operations and prepared to head out to confront him.
G Season 3
To be added.
G Season 4
Kai appears in episode 26 in Card Capital waiting for Aichi. After Aichi arrvies, Kai briefly talk to Aichi before leaving the shop. After the cardfight between Chrono and Aichi, Kai arrives with Ibuki to meet Chrono, Aichi, Shin and Kamui as well. Kai then witness Ibuki fighting Chrono with Chrono sucessfully pulling off Interdimensional Dragon, Beyond Order Dragon and win the game. Afterwards, Kai drives his friends to meet Nome Tatsunagi and got more information about Diffride and Chaos Breaker and Shiranui. After attending Aichi's homecoming party, Kai was tasked by Ibuki to search for Chaos Breaker. Kai then meet up with Arata and Makoto at the airport and stating all of them will be searching for Noa/ Chaos Breaker. While travelling with Arata and Makoto, Kai will constantly cardfight them to train ti get stronger and improving their skills. Kai then inform about Ibuki Chaos Breaker's ambitions which allowed Ibuki to save Kanzaki from being taken over by Chaos Breaker after the latter broke free from being Diffriden by Claret Sword Dragon.
G Season 5
Kai would meet up with Miasaki and Kamui in Hong Kong while eating with Arata and Makoto at a resturant. When Kai, along with his friends, when to Relics and meet Darkface, whom had set up a trap for them. After saving Arata and Makoto from being trapped by Darkface, Kai fought against Darkface and manages to overwhelm and win against Darkface.
Kai would later be present at North America's Branch with his friends and other strong cardfighters to protect the last two Zeroth Dragons from being claimed by the Apostles and allowing Gyze to truly awakens. Kai would later meet Chaos Breaker along with Aichi. After Chaos Breaker traps them in a subspace of Relics, Kai and Aichi would engage with a tag fight with Chaos Breaker. In the battle, Chaos Breaker would lock his and Aichi rear-guards with the skill of Chaos Breaker Crisis and Death Star Vader, Chaos Breaker Arusani. During Kai's turn, Kai would use the skill of of Dragon Overlord "The Destiny" to remove one of Aichi's locked card in the front row and opened up his board. Kai then Strides "The Purge" and manages to push Chaos Breaker to 8 damage but was not enough to finish him. Chaos Breaker then summons his Zeroth Dragon of Destroy World, Stark to win the game but with the combined efforts of Aichi and Kai allows them to survive that turn. After that, Aichi manages to win the game with Blaster Blade. Although Kai and Aichi the game and freeing Noa from Choas Breaker, they were unable to stop Chaos Breaker in his astral form using his soul to reactivate Relics. Kai, Aichi, Makoto and Arata then were brought back from the subspace of Relics.
After Gyze assume his goal of returning everything to nothingness, Kai was among one of the fighters that resisted against Gyze's nothingness.
In chapter one, he is shown to be fighting Morikawa in a cardfight. He wins against Morikawa. Miwa comes out saying that Kai is the best cardfighter even asking Misaki if there was any other cardfighter that are as good as Kai. Kai went to step out leaving Miwa and the others. He wonders if there was any good cardfighters at all and mentions that he would never get any better than what he is now. He and Miwa were at Card Capital when Morikawa came out again to challenge Kai once more though Kai rejected the invitation when Morikawa pulled out Blaster Blade. Miwa was outcome with joy at that the fact that Morikawa had such a card and asked to cardfight him for the card. Kai was shocked to have seen Blaster Blade wondering where did Morikawa came upon the card. Miwa was able to win against Morikawa making him the new owner of Blaster Blade, but Kai took the card to see if it was the same card. Aichi came running through the shop begging Morikawa for his card back though of course he lost the card to Miwa. Aichi then asked if he could have it back only for both Kai and Miwa to answer that he must win it back through a cardfight. Although Aichi was shy about cardfighting, he admitted that he had a deck and willing to take a challenge from Kai. Since it was his first battle, Kai taught him the basic of the game and gave him Blaster Blade back seeing that his deck probably needed it. Aichi won against Kai and told Kai that he was glad to be able to meet him, saying also that it was fun playing against him.
In chapter 2, he and Miwa is waiting in Card Capital for Aichi to come. They greeted him. Miwa and Aichi fought against each other. Miwa won the battle and said that he was the greatest cardfighter. Kai countered that he always loses to him, but Miwa countered back saying that Aichi won against him. Kai then said that they should cardfight only to be interrupted by Kamui as he made his way to the shop. Kamui asked who was the strongest cardfighter. Miwa said that he was, but Kai said that he lost to him, causing him to say that he lost to Aichi, only for Aichi to say that he lost to Miwa which in turned caused Kamui to spin around in confusion. Kamui decided to fight against Miwa and won. Kai told Aichi that he should go against Kamui. Aichi said that he wasn't good though Kai said that he won against him so he should be able to have some skill learned already. Aichi won against Kamui which caused Kamui to say that he will be more like Aichi. Then Miwa said that he should be more like him and not Aichi. This, of course, caused Kamui to see the circle again. Kai is shown smiling at his friends.
In one chapter, it was mentioned by Miwa to Aichi that Kai had planned to make a deck with Blaster Blade back when he had the card. Of course, Kai told him to not bother with this. Aichi was amazed and shocked to know of this.
Back when he was younger, he used to sleep on the park bench. He was awoken by Miwa who brought along a classmate who Kai doesn't even know even though they are classmates. He told Kai that Ibuki was going to teach them how to play Cardfight!! Vanguard. Being the hothead he was, he kept losing to Ibuki. Seeing this, he decided to go home to make his own deck. At home, he began to try to image a winning picture and found one. The next day, he asked Ibuki to fight him. Ibuki was surprised at him using a Royal Paladin deck. Kai said that it was a new clan that focuses on using magic and old tech together. He surprised Ibuki even more when he used Blaster Blade, a unit that is noted by Ibuki that can still grow, in his deck. He then used Blaster Blade Burst to win the battle. Ibuki was happy that Kai was doing something fun. Kai was shown to be walking away when a familiar someone walked along the same path too.