Yo-Yo Girl Cop

Undercover Sukeban Deka operative tasked with infiltrating Seisen Academy. She adopts the name Saki Asamiya and wields a hi-tech steel yo-yo to defuse threats. The mission strains her relationship with her mother and pushes her to balance danger with care for innocents. Her resolve and resourcefulness define the film's core.

A former school janitor who becomes the mastermind known as Romeo. He kidnaps Saki and drives the Enola Gay plot with strategic ruthlessness, manipulating others to achieve his ideology. His charisma masks a dangerous ruthlessness and a willingness to sacrifice others to advance his aims.

Leader of a powerful clique at Seisen Academy and Romeo's lover. A former Tokumei Keiji operative, she wields a blade-equipped yo-yo and exploits the school's influence to spread her ideology. Her cleverness and combat skill pose a formidable challenge to Saki.

A bullied student who befriends Saki and reveals her forgotten anti-bullying network. She becomes a hostage and a key link to Kotomi's past, providing emotional stakes and a reminder of vulnerability in the school’s social hierarchy.

A bullied schoolgirl who once helped run an anti-bullying site with Tae. Kotomi falls under a traumatic influence and later contributes a crucial clue by naming Jirou Kimura, revealing the true identity behind Romeo. Her arc underscores the consequences of social cruelty and manipulation.

Japanese inspector who oversees Kira's mission and informs Saki of her mother's deportation. He acts as a morally complex authority figure, balancing duty with concern for Saki's personal life and the escalating danger of Enola Gay.

K's mother, deported to Japan after a separate incident in New York. Her struggle and the threat of deportation drive K's sense of responsibility and set the stakes for K's undercover mission.

One of the two students targeted by bomb threats; Higashiyama is captured when Saki pursues the case, illustrating the danger faced by students who are drawn into the Enola Gay plot.

A mysterious figure linked to the Enola Gay plot and a potential antagonist. The character’s presence adds a layer of threat and control over events, intensifying the sense of conspiracy around the school and the city.