Kouu has long, light colored hair and two horns on his forehead. He wears a complete military uniform consisting of a uniform top, pants, boots, and a cloak.
As a lieutenant general, Kouu takes his work seriously. Although he cares about his sister, he will deny her wishes if necessary, such as not allowing her to use the blimp to teleport Sudou Kaname and the others back to their own world. He is also reasonable, as he was willing to honor Kaname's requests when they surrendered.
Sigil: As the leader of the royal guard and Kukuri's older brother, Kouu has an unnamed sigil which he seemingly uses in conjunction with his katana, cutting through an entire room including the people and objects inside of it, though it is unknown what it actually does.
Equipment: Kouu wields a katana.