Harumoto succeeded to a house at the age of seven, after his father's death in 1520. While still a minor, he was supported by his caretaker Miyoshi Motonaga. In 1531, Harumoto defeats Hosokawa Takakuni. He feared Motonaga who had got credit and killed him next year. After that, Harumoto ruled the whole area of Kinai (Yamashiro Province, Yamato Province, Kawachi Province, Izumi Province and Settsu Province) and took hold of the Ashikaga shogunate as the Kanrei.