Suzu Saien is the senior president of Torauma High School's science club. She first meets the protagonist when a falling human anatomy model injures him, and she subsequently indulges his persistent belief that she rebuilt him as a cyborg. While outwardly displaying indifference or passive curiosity towards the club's bizarre happenings, she facilitates his delusion partly for her own amusement. Her intelligence is evident through her academic standing and occasional knowledge displays, yet she frequently allows other members' eccentricities to drive club activities into chaos, suggesting an underlying enjoyment of unconventional situations.

Physically, she has brown hair, green eyes, and consistently wears a lab coat over her school uniform, often with leg warmers. Beyond humoring the protagonist, she provides a stabilizing presence within the club's dynamic, subtly guiding interactions while enabling the eccentric behaviors of others. Her background lacks detailed personal history outside school, though her leadership implies responsibility and capability in managing the club's unconventional affairs.

The narrative's conclusion reveals an alternative identity: she is a therapist overseeing a mental health facility. The science club scenario is an elaborate therapeutic construct where patients collaboratively build a model city and inhabit imagined roles to aid psychological recovery. This twist redefines her earlier actions as a deliberate rehabilitation strategy, culminating in the patients' discharge and transition to independent living. Her portrayal remains consistent across all adaptations, including the OVA series, without significant backstory expansion or development beyond these core functions.