煌速聖姫パラスアテナ

Takuo Shimoda was a sullen shonen who got bullied at school.

He only kept attending because of Momoka Himesato, a pretty and sympathetic classmate. He liked to be around her -- or better said, their friendship was his secret masturbation fuel. But Momoka's friend Sakuya Otonashi, the class president, found out Takuo is fapping to Momoka and got between them. Takuo lost the one thing worth living for, and directed his full hatred at Sakuya, imagining graphic rape fantasies.

That was when Takuo learned Momoka and Sakuya were, in fact, defenders of justice known as "Palace Athena", battling the "Baru Empire" invaders from another dimension.