On October 24 of the same year, Nishioka fought a mandatory bout against Rendall Munroe at the Ryōgoku Kokugikan, and defeated him by a convincing unanimous decision to extend his defending streak to five matches. Nishioka strongly desired a unification match with the other organizations' champion especially after that. When Nishioka was named Japan's Fighter of the Year in 2010, he received a video message from Fernando Montiel demanding a fight at the awards ceremony in January 2011. Nishioka said he was willing to fight anytime soon afterward and his camp intended to arrange a match, but the contract was not finalized as Montiel lost to Nonito Donaire in February. On April 8, 2011, he knocked out Argentina's Mauricio Javier Muñoz in the ninth round in his sixth defense which was moved from the Ryōgoku Kokugikan in Tokyo to the World Memorial Hall in Kobe due to the Tōhoku earthquake.