Hosokawa Masamoto

was a deputy-shōgun, daimyo and shugo of the Hosokawa clan of Japan, and son of Hosokawa Katsumoto. Masamoto was appointed to the rank of deputy-shogun in 1486, but lost this status to his rival Hatakeyama Masanaga. His childhood name was Sumiakamaru (聡明丸).

When the Shogun, Ashikaga Yoshihisa, died childless during the year of 1489, Masamoto supported the nomination of Ashikaga Yoshizumi as successor in opposition to Ashikaga Yoshitane. Masamoto thought that the post of deputy-shogun would return to the Hosokawa clan. After Yoshitane became the shogun, he was deposed by Masamoto in 1493, setting a pattern that marked further decline of the Ashikaga Shogunate.

To combat the faction led by deposed Yoshitane and Masanaga, in particular to help with a stalled assault on Hatakeyama Yoshihide at Konda castle in late 1505, Masamoto forcefully enlisted the Ikko-ikki armies in 1504 led by the Honganji temple, though some factions continued to support Yoshitane.

Family Father: Hosokawa Katsumoto Mother: daughter of Yamana Sōzen Sister: Tōshōin Adopted Sons: Hosokawa Sumiyuki (1489–1507) Hosokawa Sumimoto Hosokawa Takakuni