Kourin Tatsunagi is a main character of the second arc of the Cardfight!! Vanguard (V Series Anime). She is a member of Ultra-Rare, and was co-founder of the Miyaji Academy Cardfight Club, before her fate as a Called Walker erased her from everyone's memories. During the fight against Wandering Star Brandt, she becomes the embodiment of Blaster Arrow, who is one of Monarch Sanctuary Alfred's strongest soldiers.
She is jokingly referred to as a "tsundere" by her friend and clubmate/classmate Naoki Ishida. She is strong and determined, but slowly becomes loving and defends her friendship and cherishes the bonds she created while at Miyaji Academy. She knows of her fate as a Called Walker, but she isn't deterred by it, being thankful for her friends for making her time at Miyaji Academy great. She was forced to become a PSYqualia Zombie, and struggled fought against its control, losing to it in the end, and regrettably forces Naoki to become a Zombie, who in turn makes Aichi Sendou into a Zombie. She is best friends with Misaki Tokura, and will likely miss her the most.
Kourin has long blonde hair, with half of her hair being tied up into a loop ending in a ponytail. She also has green eyes. She's mostly seen wearing either her Ultra-Rare uniform, or her Miyaji Academy school uniform.
Kourin's only appearances through the first arc are through the ULTRA-RARE advertisments throughout the world. She had no interaction with any of the cast aside from her history before becoming a Card Walker for Taktou. It can be assumed she was an ordinary girl that Taktou Tatsunagi found worthy enough to become her vassal and seal her original memories and personality away so she could assist him better.
During the Asia Circut Championship, she presents Aichi with the first place trophy and shows off her distant demenor by doing so. Sometime after, she enrolled in Miyagi Academy under the name Kourin Tatsunagi and started going to school where she met with Aichi again. Similar to her history in the original anime, she becomes Aichi's second club member to join the Vanguard Club and imposes the restriction that only those who beat her can join the club in an effort to get rid of those who would only join just because they wanted to hang around an idol. She battled the students many, many times and each of them lost to her and her Gold Paladin deck. Eventually she lost to Naoki Ishida and allowed him to join the club.
Her role in the story still seemed to be similar to the original anime's counterpart as when Takuto was 'deleted' and the will of Planet Brandt was able to inhabit his body, it affected his vassals and caused them to turn on their own allies in an effort to further Brandt's own goals. Kourin was eventually defeated and returned to normal and witnessed Aichi fight both Kouji Ibuki and Takuto one final time, joining Aichi as Blaster Arrow in the final battle to determine not only the fact of Earth and Cray, but also Vanguard. Aichi would win and therefore, as in the original, once time had passed, Kourin, as well as the world this time around, would have their destiny's rewritten, leaving Kourin to have never becoming a Card Walker and never interacting with Aichi or his friends. In spite of time being 'corrected,' Misaki wears a ribbon in her hair that Kourin gave her and the other Vanguard club members get a faint feeling that someone is missing so her presense is still felt but to a lesser extent.
After the timeline was rewritten to erase the damage done by Kouji, Kourin still went by Tatsunagi and was still a member of ULTRA-RARE along with Rekka and Suiko. Eventually, she learned from Norne, the new head of the Tatsunagi family, that the world's melody, the timeline, was rewritten, to repair the damage done by Ibuki Kouji's deleting and the effect it had on the world's fighters, including Suiko, who continued to have no passion for Vanguard. She would slowly start to regain her connection to the Miyaji Cardfight Vanguard Club when they entered the Vanguard Kousen and fought Fukuhara Academy in the finals. There, during the final match between Ibuki and Naoki, she repremanded Naoki for fighting cowardly and told him to fight him his way. This surprised everyone, including her, as she did not know why she did that. It was thanks to that encouragement though that led Naoki to defeat Ibuki and take the title.
After the award ceremony, The core members of the club and Kourin met on stage and connected once again, but still had no idea why they felt the way they did. Kourin jokingly said about becoming a member of the club and having to beat a current member to do so, which lead to her facing off against Aichi in a special exhibition match. During the match, Naoki recalled that beating a member was a rule to join the club, but could not remember who enforeced that rule and who it was that he beat in order to join. Kourin defeated Aichi using her ace, Platina Ezel, and became an honorary memeber of the club, promising to visit when she had spare time.
Sometime after the tournament, ULTRA-RARE had to go abroad and leave Japan to cater to other events around the world. While saddened by this, Aichi reaffirmed that while they may be apart, and maybe their bonds were broken once before, they were able to reconnected and promise to stay connected forever as long as they continue to love and play Vanguard.