Ryu Tachibana serves as the right-hand man to Kentaro Yamamoto in the Inugane Yakuza Group. After a critical failure, Ryu and his comrades faced a brutal ultimatum from boss Kimanjiro Inugane: undergo sex reassignment surgery in Thailand and train as idols, or die by seppuku with their organs sold. Choosing survival, Ryu transitioned, adopting the female identity Mari Tachibana, and debuted with the idol group Gokudolls.

As Mari, Ryu embodies the "cool" member persona, attracting fan letters that provoke jealousy, particularly from fellow idol Chika. Mari possesses a profound aversion to sweets, a trait that ended a past romantic relationship. This dislike persists post-transition, complicating idol activities; Mari once vomited after forcing down cake during a TV appearance. Physical complications from the surgery include chronic hemorrhoids and other anal afflictions, occasionally causing disruptive incidents like abrupt bleeding during intense moments.

Family history adds complexity: Ryu's father, a former yakuza, is transgender. This background informs Ryu's own forced transition, though their relationship remains largely unexplored. Post-transition, Mari navigates challenging romantic and sexual situations. An attempt to offer herself to personal idol, actor Hitoshi Takamura, failed, leading to disillusionment. Later, Mari developed a relationship with a lesbian nurse treating the surgery-related hemorrhoids. Tensions also arise with Kimura, the group's assistant, whose fan devotion to Chika strains their former underling dynamic.

Internal conflict between Ryu's yakuza past and Mari's idol present manifests through clashes in behavior, such as retained masculine mannerisms or expressions of disgust at male attention. Scenes depicting Ryu's male persona interacting with Mari highlight ongoing identity struggles. These personal battles occur alongside the group's navigation of idol life, including public performances and fan interactions where Gokudolls' lyrics often conceal hidden yakuza themes.