Sato, in his third title defence, tired as the fight reached its latter stages and was stopped by the hard-hitting Srisaket in the eighth.
“I was in perfect condition up until the fight, but I was unable to fight as well as I can,” Sato said.
“I punched but he never drew back. He was strong.
“In the latter half of the fight, I tried to look for a spot to turn things around, but I was just too exhausted.”
Srisaket, 26, is now on 19-3-1, with 18 of those wins by knockout. Sato, 29, is now 26-3-1 (12 KOs).
No Japanese male fighter has won a world title fight in Thailand in 18 attempts.