Warikitta Kankei desu kara.

Also known as: 割り切った関係ですから。, Warikitta Kankei desukara., It's a Detached Relationship, Toxic Love Affair, 私立わりかん幼稚園, Shiritsu Warikan Youchien, 不談感情的關係。

by FLOWERCHILD

Kaburagi Aya, a highschool student who is at the bottom of the school caste, and Kurosaki Sei, a teacher who was oppressed by a trauma from the past, get to know each other through a dating app. With ulterior motives from both side, the relationship between them gets distorted gradually... (Source: Ichijinsha, translated) Note: Includes an epilogue chapter and a four-chapter extra story