Coming from unknown beginnings, Yoshitsugu could have entered Hideyoshi's services as a low rank kōshō or became Mitsunari's yoriki in the mid or late 1570s (either in his mid teens or mid-late twenties). Several stories will state that his intellect and charm had earned him many friends, but the legitimacy of the claims are still debated. His early achievements with the Hashiba family are not known, but most sources argue that he was among the 700 or so named individuals who sided with Hideyoshi after the Incident at Honnōji. He joined Katō Toranosuke, Fukushima Ichimatsu and other kōshō to take Nagahama Castle away from Shibata Katsutoyo, Shibata Katsuie's nephew. Hideyoshi has been romanticized to have said the following for Yoshitsugu at this time, "Give me a million troops and I would love to see him guide them."