I'm the Hero, But the Demon Lord's Also Me, manga volume 2 featrues story by Akiyoshi Ota andart by Tatsuya Endo.

Ordinary (?) high schooler Yuuma Tsugari possesses the power of both the hero and the demon lord, and so far, it’s caused him nothing but trouble! Frequent visits from otherworldly guests are one thing, but now, the princess's younger sister and the Demon General are at each other’s throats, and their rivalry’s just getting started! Will Yuuma ever be able to have a normal life again?!