Ryo Akaho suffered a second-round knockout defeat to Pungluang Sor Singyu of Thailand in their fight for the vacant WBO bantamweight world title on Friday.
It was top-ranked Akaho's second crack at a world title after losing to then-WBC super flyweight champion Yota Sato in 2012.
Tomoki Kameda vacated the WBO bantamweight title in April.
That move came after the World Boxing Organization announced it would not authorize a proposed unification bout between Kameda and Britain's Jamie McDonnell.