Atsushi Sakai is a Japanese professional wrestler better known under the ring name Kai (stylized in all capital letters). Best known for his work in the All Japan Pro Wrestling promotion, Kai is an accomplished junior heavyweight wrestler. In August 2012, Kai announced that he was ending his junior heavyweight days and becoming a heavyweight wrestler. After taking a seven-month break from in-ring action, Kai returned to All Japan in March 2013, now working as a heavyweight wrestler. However, the following July, Kai quit All Japan following a change in the promotion's management and joined the new Wrestle-1 promotion.