An Archmage who has lived for over a thousand years. Long ago, he reached the pinnacle of magic and discarded his physical body and worldly desires to become a Lich, taking the form of a skeleton. He can assume his living appearance if he wishes, which is that of a very beautiful man with long silver hair and green eyes. Usually, he floats around as a skull in his Lich form, his eye sockets glowing with a green light. Although he discarded his desires and placed them in a phylactery, his emotions have not vanished. He feels joy, anger, and annoyance, and when his emotions fluctuate wildly, he remarks that his phylactery might break. He retains his youthful appearance from when he was a prince of a kingdom. He is the Lord and Principal of Einrogard, where he raises students. He believes that the harsh and dangerous environment of Einrogard is what breeds true mages. He enjoys forcing students into predicaments and finds pleasure in their suffering. He even orchestrates raids on them. He encourages students to steal or scam, saying it's fine as long as they don't get caught; he only sends them to the punishment room when there is physical evidence. He does not punish based on suspicion or testimony alone (though he gets very annoyed and finds it bothersome). Due to the school's massive budget issues, he engages in psychological warfare with the Emperor and bureaucrats. The bureaucrats try to save money, while Osu uses various persuasions and occasional threats to secure the budget. He often takes a low posture before officials (a groveling Archmage...). He considers graduates and current students to be idiots and gets the biggest headaches when they cause trouble. ('Tell those idiots not to cause trouble, thinking they're actually doing something.') He has a surprisingly childish side and shows behavior unbecoming of his age, such as enjoying teasing others. He doesn't tend to stand on authority, but he likes showing off his magical abilities or receiving compliments on his bones. He is proficient in all fields of magic and is a Grandmaster of Necromancy, commanding a vast number of Death Knights. These knights, who were honorable warriors in life, serve their master, the Principal, but they don't necessarily defend his personality. Sometimes, they even betray their master.