Kokoro has never fit in, and lifelong isolation eroded her self-worth. In this adult campus-role setting she remains alone, admiring a gentle teacher loved by everyone while believing she is nothing special. One day she notices his phone pointed at her and realizes he is secretly filming. The joy that he may be looking only at her makes her accept his forbidden habit and ask him to keep watching and recording. Voyeurism begins a relationship of repeated taboo sex in the library and infirmary.