User blog comment:Jopjopjop/Volume 19 Spoilers/@comment-76.109.26.131-20150308013516/@comment-1359322-20150308040607

"…….He does speak with sarcasm like always. He’s a person with ultimate-class power among the entire factions in the world. The Emperor of Heaven. The Warrior-God, who defeated the God-of-Battle, Asura….. There was something I wanted to ask this Emperor-of Heaven. It has something to do with the incident at Kyoto involving the terror done by Hero-faction."

Taken from Volume 10. Remember DxD follows its own version of Myth. Do you think there are such things as the Four Great Satans, Four Great Seraphs, Evil Pieces, Brave Saints etc. No. Ishibumi created those terms and stuffs.