She helps them run the cardshop PSY, and is a member of Team Ultra-Rare.
Kourin has long blonde hair while half of her hair is tied, she has green eyes and mostly seen wearing her white normal clothes or her Miyaji school uniform.
While on stage Kourin gives the impression of a smiling idol, in real life she is serious and level-headed, as seen when she challenged people to defeat her to earn their way into the Vanguard fight club at Miyaji so that the club would be serious (and to keep out her fans). She can also be extremely abrasive and confrontational as seen when she kept opposing Misaki joining the Miyaji Vanguard club. Never the less she comes to care for her friends in the club, and to respect Aichi as the team leader, so much so that she was unable to go through with fighting him to Reverse him.
When reversed, Kourin is shown to be cold and ruthless, and her feelings for Aichi turn into a desire to possess him for herself, as she stated when she fought him under the ancient tree to make him hers through reversing him. She also seeks to preserve her new memories of Aichi and the cardfight club due to losing her old memories when she was summoned by Takuto, considering her memories of Aichi to be her whole world.
In season 4, she was willing to cooperate with the Quatre Knights to protect Aichi, even making enemies out of Kai and his mates. However, it was stated by Misaki that in her heart, she was crying and was willing to even use the clan that brought darkness to protect the one she loves. On some occasions, she took some of Aichi's Link Joker powers to lessen the pain that it caused, despite her safety being compromised. This dedication was traced back to the time she was unconsciously called out by Aichi in his attempt to prevent Link Joker from leaving his body. Despite that, she wanted to return to the lives they had before the Invasion together with Aichi and the Cardfight Club.
As she was called out by Takuto to protect Cray, her current memories vanish if Takuto disappears. However, her memories return as Link Joker stayed behind with Aichi as the clan's vessel. She also was able to take in Link Joker's powers, with her dedication to be with Aichi's side manifested in a form of a card, Companion Star Star-vader, Photon as her avatar. When the card disappears, her memories also fades away. After taking in more of Aichi's powers, she was able to create a pocket dimension similar to the Quatre Knights, in which the consequences that the miasma engulfs her after her loss and Aichi's assistance was required to stop it.
She first appeared in episode 6, along with the rest of her sisters. She challenged Aichi Sendou to a fight after he was able to activate the machine that made the cards virtual. She was unsure of Aichi's skill, thinking he was weak, but decided to fight him anyway. After a close match, she won, but told Aichi it was a good fight and that he should enter a tournament.
She is next seen in episode 16, as a hologram with her sisters, welcoming players to the regional tournament. In episode 18, she sings with her sisters during a break at the tournament. After the song, she's surprised to see Aichi make it to the finals.
Throughout the match between Team Q4 and Team Handsome she comments about the the matches with her sisters. During Aichi's match, she and her sisters agree that Aichi was different during his fight against Gouki. They then gave Team Q4 medals for winning the tournament.
In episode 23, Suiko invites Ren Suzugamori to test his skills. Kourin fights him, using the same deck Ren was given for the fight. Although she had the upper hand for part of the fight, the battle ended in her loss. Afterwards, when they're talking with him, he says she's a good fighter, but she's not on his level. Kourin gets angry at this, but is held back by Suiko. As Ren leaves, she says she will never acknowledge him. Later in the anime, she returns to fight Aichi, but loses to his new Shadow Paladin deck that was given to him by Ren.
In episode 70, she met Aichi alone in the streets of Singapore, where she informed him about the identity of the mysterious boy he met, Takuto Tatsunagi. Afterwards she gives Aichi one of her own cards to use in his deck, Incandescent Lion, Blond Ezel, an act that Rekka considers meddling. In episode 92, she fought against Aichi using an Angel Feather deck.
In Season 3, she transfers to Aichi's high school to get a feeling of public life, under Takuto's instructions. However, she still does not know why Takuto made the decision in the first place. She drew a lot of attention to herself since she is an idol. Later she joined the Cardfight Club that Aichi started after seeing how much work he was putting into the whole thing. Naoki Ishida wanted to join the club, but Kourin said that he needs to defeat her in a cardfight in order to join the club. He later defeated her and was accepted into the club. The club was having a hard time gathering members since she kept defeating all the recruits and that most just want to stay close to her. Shingo Komoi challenged Naoki for entrance into the club, because he thought that Naoki didn't deserve to be in the same club as his idol which at first seemed to be Kourin though it later turned out that it was Aichi instead. After gathering four members, they needed a fifth member to make it official. It was near the end when Misaki Tokura declared that she is their final member. Kourin was at odds with her, and like any members wanting to join, she must face her in order to be granted entry. However, Misaki will be fighting Aichi instead. The problem was that if Aichi lets Misaki win because he goes easy on her, then Kourin will leave the club, prompting Misaki to say the same thing to him too. After seeing Misaki play at her hardest, she decided to let her stay in the club.
In episode 140, it was revealed that Kourin had become Reversed during a fight with Aichi. But during the fight she found herself unable to ride her "new ace" as she did not want to harm Aichi and respected him too much. As a result she ran into the forest. She is soon seen returning to Miyaji Academy with the Student Council Secretary stating that she will not hesitate anymore and proceeds to fight Kamui revealing her new ace Broken Heart Jewel Knight, Ashlei "Яeverse" as well as her new Quintet Wall Sentinel, Summoning Jewel Knight, Gloria, which managed to save her and claim her victory in the end thus Reversing Kamui just as Aichi and the others had just gotten back.
In episode 157, she faces off against Aichi to give Reversed Takuto time to control the recently absorbed Takuto. It is revealed that Kourin and her "sisters" were called by Takuto who had sealed away her memories in order to assist Takuto in helping to protect Cray and Earth. While she lost her old memories, she had gained new ones with Aichi and the others and was desperate in protecting them as if her role as an ally of Takuto were to end, so would her memories with Aichi and the others. In the end, Aichi, who was already struggling to suppress his Reverse, manages to defeat and un-reverse Kourin leaving her with Misaki while he goes on to face Takuto. At the end of the season, Kourin seems to have disappeared as her sisters appear to be performing without her.
In the beginning of Season 4, evidence of her absence is shown in magazines and concerts in the first few episodes. Little to no people seem to remember her so it is presumed that she had disappeared like Aichi. The only individuals who specifically know her are Kai and Misaki, who has her hairband. However, in episode 176, she reappears and is apparently assisting the Quatre Knights in keeping Kai's group away from Aichi. She fights Kai in Gaillard's place.
In the next episode, using a Link Joker deck which shocks Kai and the others. However, Kai and Misaki both notice that she is not reversed. When Kai brings out Blaster Blade Seeker, Kourin figures out that Blaster Blade chose to go to Kai. After confirming that Kai and the others feelings about finding Aichi are genuine she gives them an image where Aichi tells the other he no longer wishes to see them. finally, Kourin defeats Kai but he is not reversed, instead Kourin takes Blaster Blade with the intention of giving it back to Aichi.
In episode 189, as all 4 of Aichi's seals were released, the Sanctuary collapses. She was saved, by Neve, from the falling pillar and rushed to the area where Aichi was. Seeing that Aichi was trying to hold back Link Joker, she used her deck to absorb some of Link Joker’s miasma. When she insisted for more, she was stopped by Aichi, saying his thanks before he lost consciousness. She tried to keep Serra at bay by fighting him but was locked up by Serra's ice chamber. When Serra tried to wake Aichi up, she tearfully shouted for him to stop. Fortunately, his actions were stopped by Kai, Naoki, Ren, Leon and Gaillard. She was free from the ice chamber by Gaillard's flames and witnessed the battle between Serra and Gaillard.
In episode 191, she insisted that she will be Kai and his mates next opponent. Despite Gaillard telling her to stay by Aichi's side, she replied that there is nothing she could do for him other than to fight them. Using the Link Joker miasma she absorbed from Aichi, she created a field for the cardfight. It was revealed in the flashback that since the reversed Takuto was defeated, she had lost her memories. When she was wandering on a busy street, she heard Aichi's tormented voice and was transported to the Sanctuary. Realizing that her memories had returned, she learned about Aichi's situation. When his powers acted up again, causing him to feel intense pain, she held his hand and absorbed some of it, causing Aichi to relax and a card to appear. It was at that time she had decided that she would protect Aichi at all cost. Despite her determination, she was defeated by Naoki. As she lost, the miasma consumed her. Flashbacks of both Aichi's and her life before the Link Joker invasion appear and she realized that she wanted to return to them. Fortunately, Aichi woke up and saved her from the Link Joker miasma. She fainted after apologizing to Aichi.
She was carried to the throne by Aichi and he absorbed the powers she had taken in from her deck. She regained consciousness and realized that he had absorbed back his dark powers. She witnessed Gaillard and Kai's final battle and got concerned when Aichi's powers are acting up again. During Aichi and Kai's battle, she realized that Aichi Legions his avatar, Star-vader, Blaster Joker with her avatar, Companion Star Star-vader, Photon and he was not giving in to Kai and his mates. After Kai won and Aichi fainted due to the after effects of the Seed's power, the moon palace breaks down and she talked to Aichi one last time in the form of their astral bodies. She told him on how she was grateful to be reunited with him again and was able to help him. When the card Photon from Aichi's scattered deck disappears, she explains that her memories will disappear as Photon represents her. She returned back to Earth when the palace was completely broken down and returned to Ultra Rare with Suiko and Rekka. She managed to took a glimpse of Aichi for a long time after he saw her by the river.
She is more reserved and does not talk unless needed. When it comes to cardfights, she is very serious and is known to never hold back. She, along with Suiko and Rekka, is part of the international idol group called Team Ultra-Rare. She later on develops a good standing relationship with Aichi and his friends.
Unlike her anime counterpart, she uses a Gold Paladin Deck that focuses on Ezel instead when she enrolls into the same school as Aichi. She does, later on, join the club Aichi made, though she did challenge him to a Cardfight to earn her stay in the club, or rather she wanted to test him. When Naoki said that he wanted to join the club, Kourin said that he must defeat her in order to join. After a difficult match since he was still a beginner, he won his stay. When Misaki wanted to join the club, she was the one who battled her and won against her. Kourin wanted to test Misaki to see if she had PSY Qualia, though it turned out she did not have it as it seems.
In Volume 6, it was mentioned that although she does live with Suiko and Rekka, they are not sisters at all and they do not share the same blood, unlike in the anime where they are sisters though they never mentioned their parents.
Kourin has a good relationship with her older sister. She listens to Suikos instructions, though she is often irritated by her lackadaisical attitude.
Kourin has more of a rivalry with Rekka than with Suiko due to Rekka's strong willed nature as Rekka does not often listen to Kourin's instructions.
Kourin has had an interest in Aichi since they first met. She went out of her way to help him a number of times, such as presenting him with blond Ezel, and was sad when he became corrupted by PSY Qualia. After forming a close friendship with him at Miyaji she came to see his strength and leadership, and gained respect and affection for him, so much so that she temporarily broke free of her reverse to stop her fight with him. Suiko and Rekka have also been known to tease her about her feelings for him. Her worst fear is losing her memories again, particularly her memories of Aichi, and seems to have fallen in love with him by the end of Link Joker.
She appears in Legion Mate as an ally of Gaillard, wanting to protect Aichi from Kai and the others.
Because of their similar personalities Kourin and Misaki butted head the first few times they met. The vanguard club nearly didn't form because Kourin kept abrasively challenging Misaki's motives and determination. They eventually came to understand each other and formed a somewhat close almost sisterly relationship.