Nene Todoroki is a first-year student at Ōsai Academy who advances to second year. She serves as head of the Robot Research Club and ranks fifth in her grade academically. Her personality blends technical brilliance with overt sexual preoccupations. She demonstrates kindness by repairing electronics and creating practical inventions, such as a custom desk for her short-statured friend Suzu Hagimura. However, her primary focus is developing sexual devices like vibrators and dildos, often incorporating them into her creations, exemplified by a Medusa hairpiece with snake-like dildo components. She habitually wears these devices at school, sometimes forgetting to deactivate them, and openly discusses them with others, including Suzu and Takatoshi Tsuda.

Suzu Hagimura considers Nene her best friend, frequently inviting her for sleepovers and involving her in family activities with Suzu's mother. Despite Suzu's refusals, Nene persistently offers her custom-made devices, including a vibrator tailored to Suzu's size. Nene also extends these offers to Mutsumi Mitsuba, though Mutsumi's innocent nature prevents comprehension. Nene's relationship with Takatoshi Tsuda evolves from limited student council contact to a casual friendship after they become classmates; she gives him Valentine's Day chocolates, though he remains wary of her open discussions about sex toys.

During the second season, Nene hosts "Nene Todoroki's Trivia," presenting historical facts about sexual aids. Her presentations often escalate excessively, requiring Suzu and Takatoshi to intercede. This segment underscores her tendency to intertwine academic interests with her machine-focused fetish. Beyond her club, she assists in the school library, suggesting possible Library Club membership. Her name's kanji (轟) translates to "to roar," though this lacks explicit thematic connection. Her documented role remains consistent, portraying a juxtaposition of intellectual ingenuity and unabashed perversion through recurring comedic interactions.