18+ Furueru Kuchibiru

Kon Katakura rarely attends classes, but when she does, her behavior is poor and her performance is mediocre. When the new homeroom teacher Kurosawa arrives, the two soon end up in a relationship quite unlike other students'. Through ups and downs, the couple struggles to define their feelings for each other. The only way they are able to manifest their affection is through passionate sexual intercourse, in which they indulge day and night. Kon moves to her new boyfriend's apartment, shunning her family and classmates, in an attempt to find meaning in their half-hearted and cursory relationship.