In 1545, the shogun, Yoshiharu, resigned in favour of his son, Yoshiteru. Two years of quiet ensued in Kyoto, and then the old feud broke out once more. The Hosokawa, represented by Harumoto, and the Miyoshi, by Chokei, fought for supremacy. Victory rested with the Miyoshi. The Hosokawa's power was shattered, and Chokei ruled in Kyoto through his vassal, Matsunaga Hisahide.
Motochika, believing that Hosokawa's ultimate intention was to elevate Sumimoto to the shogunate, in which event the latter's guardian, Nagateru, would obtain a large access of power, compassed the murder of Hosokawa, the kwanryo, and proclaimed Sumiyuki head of the Hosokawa house.
Therefore he adopted three sons: the first, Sumiyuki, being the child of the regent, Fujiwara Masamoto; the second and third, Sumimoto and Takakuni, being kinsmen of his own. The first of these three was entrusted to Kasai Motochika; the last two were placed in the care of Miyoshi Nagateru. These guardians were Hosokawa's principal vassals in Shikoku, where they presently became deadly rivals.