Prana Tōsei operates as a key member of the Great Imperial Combat Revue B.L.A.C.K., a government-authorized unit defending Japan against demonic Koki through entwined live theatrical performances and covert combat missions. Her allegiance pits her against the rival Imperial Combat Revue, which aims to unveil state conspiracies surrounding the Mirai energy source and the unnatural suppression of cherry blossom phenomena.

Born on April 8, she possesses striking mint-green hair and vivid green eyes, embodying her Japanese heritage. Her exchanges with Yoshitaka Oishi—addressed with the familiar "-kun" honorific—hint at a shared history within B.L.A.C.K. prior to his defection to the rival faction.

As one of the "Noble Twelve," she collaborates closely with operatives like Saimei Kurumi and Claire Sekisho, balancing flashy stage acts to uplift public morale with lethal strikes against Koki threats. Her actions remain strictly aligned with enforcing governmental directives, with official records offering no insight into personal ambitions or ideological struggles.

Documented accounts emphasize her tactical contributions to B.L.A.C.K.’s objectives, framing her narrative through operational efficacy rather than individual growth or backstory exploration.