Saitō Dōsan
Yoshitatsu was the son of Saitō Dōsan, however, rumors that Yoshitatsu was in fact not Dosan's real son (that is, that he was actually Yorinari's son) persisted and Dôsan apparently began to think of naming one of his other sons, Nagatatsu, as heir. Yoshitatsu had come to suspect his father's intentions. Though he actually did suffer from leprosy, Yoshitatsu feigned illness and murdered his two younger brothers in 1555 and declared war on Dosan.