Chastity High

Arisawa Yuichika enrolls in an elite girls' high school attended by the children of wealthy families. Thinking of her daughter's future, her mother Chihiro tries her best to scrape together the school fees, but life for the couple is not easy. When Yuichika advances to her second year of high school, the school merges with an all-boys school to become coeducational, Tomorrow Academy. The students are excited, but a new school rule is enacted that prohibits dating between boys and girls. What's more, the rule is so strict that any student who violates the rule and has sexual intercourse will be expelled.
The student council immediately began patrolling around love hotels and other areas in what is known as the "rabbit hunt," and many students dropped out. Yuichika's best friend was also forced to drop out. Meanwhile, in order to save her mother, who was left with a huge debt from her ex-husband, Yuichika began working as a "love keeper," accepting money from violators without revealing her true identity and erasing evidence photos. The students had once given up on love, but with the arrival of a savior, the romance landscape becomes even more complicated and tangled. Yuichika had no interest in love, but after seeing the students' straightforward feelings of love and finding herself attracted to Maki Ryogo, her feelings began to change.
Eventually, after a certain incident, Yuichika decides to sue the school and demand that the ban on romance be lifted.
(source : mydramalist)