The first that we read about was Naoya Inoue, the Light Flyweight champion. Inoue was known to be competing for the OPBF title next time out against Filipino Jerson Mancio and we fully expected him to vacate the belt. He had found out that Kenichi Horikawa would be his next mandatory challenger after winning "Strongest Korakuen" and appears to have made the logical move above the Japanese scene.
The second fighter who has apparently vacated is Ryuji Hara the Minimumweight champion who defended his title just a few days ago at the "46th Phoenix Battle". Although we're not clear on what Hara's next step is we'd really not be shocked if the youngster moved up to Light Flyweight and maybe even fought Horikawa for the Japanese national title at 108lbs. The other main possibility is that Hara looks to claim the OPBF title at Minimumweight.