Nodoka Toyohama is Mai Sakurajima's younger half-sister, sharing the same father but different mothers, born after their father remarried. Their first meeting occurred during a childhood audition of Mai's, where Mai expressed a desire for a younger sister, visibly delighting Nodoka. This initial bond later fractured due to family conflict. After Mai's mother spitefully enrolled Mai in an acting troupe, Nodoka's mother retaliated by pushing Nodoka into performing arts. Fueled by their mothers' rivalry, Nodoka's mother constantly compared her achievements to Mai's more successful career, fostering a deep inferiority complex in Nodoka. She perceived Mai as effortlessly talented, feeling her own efforts were devalued, especially when Mai's return to acting overshadowed Nodoka's debut with the idol group Sweet Bullet. Nodoka displays a confident, competitive exterior with tsundere tendencies—emotional outbursts, immaturity, and a short temper, particularly around Sakuta Azusagawa. This masks an insecure interior and a desperate need for maternal approval. She struggles with practical matters like tidiness, differing from Mai, though she matches her sister academically. She harbors a fondness for beaches, stemming from living in coastal Yokohama without easy access. A pivotal moment occurred on September 1st when, after a fight with her parents, Nodoka ran away to Mai's apartment. That night, she and Mai experienced Adolescence Syndrome, swapping bodies. Forced into each other's lives, Nodoka attended Mai's school and handled her professional commitments, including modeling and interviews. The pressure of living up to Mai's reputation culminated in a breakdown during a September 12th photoshoot, where she hyperventilated and collapsed. Her turmoil intensified after a Sweet Bullet concert on September 21st. Witnessing her mother lavishly praise Mai (in Nodoka's body) for the performance, Nodoka felt profound shame and despair, leading to a suicide attempt where she ran into the ocean intending to drown. Sakuta intervened. He later confronted her at Mai's apartment with a box of heartfelt childhood letters Nodoka had written to Mai, proving Mai cherished her. During the emotional confrontation, Nodoka expressed resentment towards Mai's perceived perfection and her own inadequacy. Mai acknowledged their complicated family history, blamed their father, and reassured Nodoka she didn't need to be like her. Nodoka broke down, crying while voicing her desperate need for her mother's recognition. This catharsis, coupled with Mai's embrace and affirmation that Nodoka could find her own happiness, resolved the conflict. The sisters reconciled, and their bodies returned to normal. Following another argument with her mother, Nodoka moved into Mai's apartment, symbolizing her shift away from maternal influence and the strengthening of her sisterly bond. She expressed gratitude to Sakuta, acknowledging her understanding of Mai's choice in partner. Nodoka subsequently developed a close friendship with Sakuta's sister, Kaede Azusagawa, helping her study for high school entrance exams and attending a Sweet Bullet concert together. In later storylines, such as during December events, Nodoka is depicted living with Mai and continuing her activities with Sweet Bullet. She interacts with Kaede and fellow idol Uzuki Hirokawa, listening to new music releases. She navigates her relationship with Mai and her career while integrated into the broader social circle.