While NBA general managers are frantically working the phones to build championship rosters, Victor Wembanyama is continuing to knock out his side quests — this time, he was spotted having fun at a nightclub in Japan!!

TMZ Sports obtained video of the 7’3” center hanging out at 1OAK Tokyo early last Sunday morning … where we’re told he was chilling with some players from Japan’s pro basketball league as “Get it Sexyy” by Sexyy Red blared on the speakers.

Our sources tell us Wemby was super friendly and welcoming to all the ladies and men around him … and hung around for about 90 minutes before heading out.

The 21-year-old, of course, now has a new look after shaving his dome and opting for a buzz cut.

It’s some well-deserved R&R for the Spurs superstar … whose season was cut short after he developed a blood clot in his shoulder.

At the time, the team said they expected to make a full recovery and be ready for their training camp when it begins in October.