0-Match Champion

(from amazon.jp):

Zero matches in the ring, start!

A mysterious boy defeats a corrupt heel wrestler with a brilliant punch, a punch from a former circus star!

Tetsuya Nakanishi, who was trained as a boxer by the former world champion, Smith, is now a boxer with no fights in the ring, and he is now calling himself a "0-Match Champion" in honor of his father who was a zero fighter pilot.