 Naito moved down to the strawweight division and made his ONE Championship debut against the reigning and undefeated ONE Strawweight World Champion Dejdamrong Sor Amnuaysirichoke in his native Bangkok, Thailand on May 27, 2016.He defeated Dejdamrong by rear-naked choke in round four to become the ONE Strawweight World Champion.As the new champ, he made his first ONE Strawweight World Title defense against Joshua Pacio on October 7, 2016.