Sadayu was a prominent leader among the Saiga monto of Kii and Kawachi province and held Saiga castle. He joined the Honganji and Hatakeyama Sadamasa in resisting Oda Nobunaga and led a powerful unit of arquebusiers at the Ishiyama Honganji. Sadayu later died in 1585 as Hideyoshi was attacking the religious establishments of Kii province. One theory has that Toda Takatora arranged for Sadayu to be made to commit suicide. According to tradition, Sadayu and his men were in essence mercenaries, at first fighting in wars that did not directly effect the Suzuki domain.
- Initial text from Sengoku Biographical Dictionary (Samurai-Archives.com) FWSeal & CEWest, 2005