Mio Tsuzuki, a 14-year-old self-styled magician, operates as her group's computer hacker. She manipulates the omnipresent surveillance systems and bypasses security protocols in her highly digitalized society, hacking police networks, disabling parole robots, and circumventing city-wide lockdowns from her hidden base in an abandoned redevelopment area.

Exhibiting a cheerful, energetic, and highly sociable personality, she acts as the driving force within her friend group. This contrasts sharply with her reserved classmate Hazuki Makino, whom Mio actively encourages to engage beyond digital confines. She demonstrates assertiveness during investigations into mysterious murders, accessing confidential police data and coordinating protective efforts for her friends.

Her technical proficiency extends beyond conventional hacking; she developed a weapon of mass destruction within her apartment, destroyed by a grenade attack before deployment. She survived by concealing herself inside a protective rag doll machine, later reemerging to assist Hazuki during a police confrontation by disabling pursuing robots via the surveillance system.

Mio expresses aspirations beyond hacking, like forming a girl band with friends. She navigates the city at night without digital assistance where others struggle, operating with minimal reliance on portable monitors. Her approach is encapsulated in the statement that fooling mechanical surveillance is simpler than deceiving human observers.

Her character arc involves fostering genuine friendships in a society discouraging physical contact, pushing her group toward real-world interactions despite systemic barriers. She plays a pivotal role in challenging the dystopian structures through both technical subversion and interpersonal encouragement.