Floyd Mayweather Jr. has announced that he will fight on Dec.31 at Saitama Super Arena in Saitama, Japan against undefeated kickboxing sensation Tenshin Nasukawa in the Rizin Fighting Federation.

Mayweather and Nasukawa were introduced at a news conference on Monday in Tokyo by Rizin officials. 

The promoters said they are still working on the specific rule set and it is unknown whether it will be a boxing match, an MMA fight or a fight under different rules.

Mayweather's most recent event was August of last year where he took on UFC star Conor McGregor in the ring. Mayweather won the fight with a late-round TKO and the pair have teased a rematch ever since.