Having just turned 32 a few days before, boxer Shinsuke Yamanaka said with a bitter smile that having a birthday for an athlete at his age wasn't necessarily a pleasant thing.

But he added that he felt no decline whatsoever, but rather has room to improve to become a better fighter.

The WBC bantamweight champion, who's taking on Suriyan Sor Rungvisai of Thailand at Yoyogi National Gymnasium Annex next Wednesday, said that he'd added variations to his boxing techniques and that'd give him a stronger mental edge during a fight.