Works as a janitor at the JCC. He has been working at the JCC since Sakamoto was a student. He also raised his then 7-year old grandson Amane in the JCC. He enjoys teasing Amane, but shows slight annoyance at him skipping classes and frequently hits him on the head.

Spoiler

He is revealed to be "Database", a living student database for the JCC. His extremely precise photographic memory allows him to maintain a comprehensive bank of information on 38,764 students, which is presumably every student that ever attended the JCC. He also remembers the dates of all 783 times he hit his grandson on the head.