Chika Sugihara began as Kazuhiko Sugihara, a 23-year-old yakuza boxer within the Inugane syndicate, recognized by his permed hair. After a critical failure, Kazuhiko and two comrades avoid ritual suicide by undergoing gender reassignment surgery in Thailand to become pop idols, adopting new identities. Kazuhiko transitions into Chika Sugihara, now presenting with black twin-tails, a cultivated cute persona, and occasional masculine speech slips that defy idol norms.

Chika confronts her complicated past, facing her father's initial rejection of her new identity. She reconnects with Kimura, her former yakuza subordinate now working as her group's assistant. His romantic feelings for her idol persona create tension, ultimately leading to a relationship where he knows her history.

Throughout official media, Chika balances dual lives. She performs as the "ditsy" member of the idol group Gokudols but frequently reverts to yakuza behavior, using crude language or aggression to solve problems. A visit to their imprisoned former boss prompts him to urge them to embrace their new paths. Chika subsequently demonstrates loyalty to both worlds, protecting Kimura during a kidnapping while fulfilling idol duties and upholding yakuza values.

In the live-action film, Chika survives being shot by antagonist Seiji Koizumi due to a concealed kevlar bra. She later performs at the J-Pop Summit with renewed dedication to her group. Her character arc concludes with her accepting her hybrid existence, maintaining idol responsibilities alongside enduring yakuza brotherhood.