As Yuuta Togashi throws away his past delusions of grandeur in order to start high school with a clean slate, he encounters a curious girl climbing down his balcony. On the first day of school, the same girl, Rikka Takanashi, approaches Yuuta, exhibiting her own signs of 'chuunibyou syndrome'.
Having eavesdropped on Yuuta getting his delusions out of his system, Rikka declares him his soulmate, despite him having no interest in reentering his delusions. However, he is asked by the teacher to walk Rikka home, as she had only moved in with her older sister, Tōka Takanashi, who lives above Yuuta's apartment, the day before.
Upon arriving home, Yuuta helps Rikka move her belongings into her apartment. Later, Rikka manages to convince Yuuta not to throw away his old belongings.