Aoi Koga

Aoi is a laid-back, cool-tempered man, and the father of Mitsuki. He was the leader, guitarist, and wrote the lyrics and composed the songs for the legendary band 'Route:L'.
Aoi had a very close relationship with his band mates and friends, especially Takuto Kira, who was an orphan and viewed Aoi as a father figure.

(From Wikipedia.org)
[Edited by Tiamat]