Tera-hashi, a science otaku attending high school, was subjected to brutal bullying by his classmates every day. His only salvation was the existence of Natsu-e Tojo, an honor student who always protected him. For Terihashi, Natsu was a 'sanctuary (angel) not to be defiled' who understood him. Secretly photographing her and looking at those pictures had become his raison d'être. However, one day, Terihashi accidentally witnessed something he shouldn't have seen. That was Natsu secretly meeting with her married teacher, Yamada, and indulging in an affair on school grounds. Terihashi's love for Natsu turned into a dark obsession after feeling betrayed. The next day, Terihashi summoned Natsu to the classroom after school...
