Sithu of Pinya was regent of Pinya from 1340 to 1344. He is not mentioned in any of the royal chronicles. He only appears in a Pinya era inscription as "King" Myinsaing Sithu. Sithu, who according to the inscription succeeded Uzana I, may have been a caretaker for his nephew and son-in-law Kyawswa I of Pinya. Sithu's elder daughter Saw Gyi was married to Kyawswa I. At least one contemporary inscription donated by Kyawswa I's chief consort on 17 June 1342 disputes Sithu's claim, saying that Kyawswa I was already king.