Naoya Inoue, arguably the top pound-for-pound boxer on the planet and undisputed junior featherweight champion, returns to the ring on Friday. Inoue will defend his four world championships against Ye Joon Kim in a main event from Tokyo's Ariake Arena.

Here's all you need to know ahead of Naoya Inoue's undisputed junior featherweight title defense against late replacement Ye Joon Kim on Friday.

Japan's unbeaten Naoya Inoue said he was mentally "exhausted" after knocking out a goading Kim Ye-joon to retain his undisputed world super-bantamweight titles in Tokyo on