High school freshman Yūta Togashi was once a "chūnibyō patient" i.e. an overly self-conscious middle schooler. He wants to bury this embarrassing past and begins a new life in high school—unsuccessfully. His classmate Rikka Takanashi, a "current" chūnibyō patient, has found traces of residual symptoms on him and used the fact to force Togashi "making a contract" with her.

[Source: Anime News Network]