Ryo Tachibana served as a yakuza underling and right-hand man to Kentaro Yamamoto within the Inugane Group. After a critical mission failure, boss Kimanjiro Inugane presented Ryo and his comrades with an ultimatum: commit ritual suicide or undergo sex reassignment surgery and retrain as female idols. Ryo chose surgery and intensive training in Thailand, returning to Japan as Mari Tachibana.

As Mari, she joined the idol group Gokudols, embodying the "cool member" persona. Her popularity and frequent fan letters fueled jealousy among other members. Despite the feminine presentation, Mari retained masculine traits, including a strong aversion to sweets – a dislike that had previously ended a relationship during Ryo's life. She rejected cute gifts and resisted idol mannerisms, creating internal conflict between her ingrained yakuza instincts and idol expectations. Post-surgery health complications, particularly chronic hemorrhoids and other anal issues, occasionally caused public incidents like bleeding during performances or lectures.

Ryo had admired actor Hitoshi Takamura, collecting his films. As Mari, she attempted to offer romantic affection to Takamura, but was rejected. Family dynamics added complexity; Ryo's father, a former yakuza, also transitioned to living as a woman, creating a shared experience regarding gender identity.

In the live-action film, Mari developed a relationship with a lesbian nurse who treated her hemorrhoid condition, exploring romance within her new gender context. Across all portrayals, Mari maintained fierce loyalty to fellow transformed yakuza Kentaro and Kazuhiko, their shared ordeal forging an unbreakable bond. She struggled with public perception, swinging between resisting idol culture and reluctantly adapting to aspects like accepting fan adoration or participating in feminine activities, all while internally voicing masculine frustrations.