انیمه Grope: Yami no naka no Kotoritachi

An earthquake causes the school campus to collapse living only 4 survivors - 2 childhood friends, Fubuki & Shinichi with Takahaki and a Junior girl. Both Shinichi and Takahaki likes Fubuki, but Fubuki likes only Shinichi. Takahaki made false accusation on Shinichi having interest on the Junior, whom also likes Shinchi, in front of Fubuki to create a doubt between both childhood friends. And making use of the situation and raped the Junior and of course.... Fubuki. Leaving Shinichi in a mist of doubts.

(Source: Anime News Network)