18+ Amayakasaretai

Due to her grandmother's last wish, Kumi was forced to attend Yuugaa private high school (a school for the rich and famous). By accident, she bumps into Akichan and Fuyuchan (whom she has offered to help). The brothers called themselves the Amayaka Saretai Members. Subsequently, she bumps into Aki and Fuyu's stepbrother, Amateru, who sets his eye on Kumi, by always pestering her and raping her intentionally.
(Source: TCManga).