Conversation so far:
How long was Mike Awesome the world champion?
Mike Awesome was Brass Knuckles Heavyweight Champion for 489 days and Independent Heavyweight Champion for 291 days
What weight did Mike Awesome fight at?
Mike Awesome was a heavyweight
Who was the previous longest reigning world champ before Mike Awesome?
Atsushi Onita was the previous longest reigning Brass Knuckles Heavyweight Champion

Question: How long did he reign?
Self-contained rewrite: How long did Atsushi Onita reign?