User blog comment:B214/Azazel Cup discussion center/@comment-6341273-20170324021932/@comment-10330822-20170324142433

I don't know what you found it so absurd. He's only been a devil for a year and he's already Heavenly Dragon/Super Devil-level, meaning 20 something years in the future its no surprise he's OP as hell.

Also, its much worse than you decribed. He didn't just beat a God, he beats "ARMIES OF GODS", on the regular. What's worse, Loki and the UL knew that he'd beat them, that's why they went back in time to kill him before he became so OP. The problem is, Issei beat the army even faster than they thought. Chances are he's got an Outrage Mode just like most dragons, and when he heard Asia was attacked by Loki, he went crazy and started murdering that army Juggernaut-style.