Kousoku Seiki Palace Athena

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.

In love with one girl, hateful of the other. Knowing what he knew about the two girls, Takuo was drawn to their enemy, to bondage and treason, to the bottomless pit where his own dark rage and desire was sleeping, waiting to rise.

---There was nothing but bitterness in this world.
---Takuo betrays humanity and embraces contempt in a downward spiral of hatelust!

[From DLsite English]