Yasuaki Yamaguchi (山口康明, Yamaguchi Yasuaki, born in Gunma, Japan), known by his stage name Ya Chang, is a Japanese actor, comedian, and recording artist currently active in the Philippines.
He was a businessman in Gunma, Japan (Suburb In Tokyo) before he went to the Manila, Philippines just to meet Jopay Paguia of Sexbomb Girls. He was present always in Eat Bulaga! where he was discovered. He then became a host of MTB: Ang Saya-Saya. He appeared in ABS-CBN TV shows such as Aalog-Alog and Quizon Avenue. He also appeared in the drama Maalaala Mo Kaya to portray his own life story. He also assisted the show's crew on their first episode that was set in Japan. He recently appeared as Kenjie in ABS-CBN's Eva Fonda, acting as an antagonist for the first time. He also appeared on Dobol Trobol: Lets Get Redi 2 Rambol! as a guest and Nobody, Nobody But... Juan as a Japanese officer during Japanese Occupation of the Philippines. He also appeared as an Engineer for Lim Aviations in ABS-CBN's Be Careful With My Heart. He is also one the host of Biyaheng Bulilit Travel Show, along with Tatay Nashii and Cha-cha "Bulilit" Cañete.