一瀬グレン

Guren is a Lieutenant Colonel of the Japanese Imperial Demon Army and the commanding officer of the Vampire Extermination Unit's Moon Demon Company. He is also the one who saved Yuuichirou after his survival, and is some kind of a mentor to him as well. He teached him how to survive above ground, how to live in the Demon Army's cities, and how to use a sword. Unfortunately, he is less successful at teaching Yuuichirou obedience and subordination.

After finding Yuuichirou outside of Sanguem, the vampire city, Guren says that one of the lab rats from the Hyakuya laboratories, the company responsible for destroying Japan, is there just like the prophecy said. He tells him that he will be useful in exterminating vampires.

Guren is a wise leader who values teamwork and cooperation, determined to ensure the survival of the human race from demons and vampires. When Yuuichirou tried to join the Moon Demon Company, Guren refused to allow him to join until he made friends.

He pretends to be lazy, but he actually works hard and keeps many secrets, which he has no difficulty lying about. He plans to dethrone the Hiiragi Family. He cares about his subordinates and friends, considering them to be family even before and after the apocalypse started. 

From url=http://owarinoseraph.wikia.com/wiki/Guren_IchinoseOwari no Seraph Wiki