Koi ni Koisuru Koibito Kankei

Asako Ichijou, the student council president at a prestigious girls' high school, has been racking her brain about the ladykiller Nagi Tenma. That's the sort of person Asako is, but Nagi discovers Asako has broken school rules by bringing a shoujo manga to school...

Asako pleads with Nagi to keep it a secret, and Nagi reveals her condition: "Become my lover."

(Source: Takeshobo, translated)