User blog comment:ExtremeVelocity/Cameos!/@comment-9877332-20130818103859/@comment-3261234-20130818125433

Ah, the german wikipedia article about K-ON states that this guy is an allusion to Sōichi Negishi, who is the "normal"/public version of Krauser. It also states that Yui meets Tomoya from Clannad at some point in a hallway, but I don't recall that....maybe I just missed it because I never saw or read Clannad....