Hosokawa Michimasa


Hosokawa Clan


Bitchū Province

Lifespan:  Bunki 4/Eishō 1 (1504) to Tenbun 22 (1553)

Name Changes:  Michimasa → Terumasa

Rank:  bushi

Title:  Governor of Awa, Governor of Musashi

Clan:  Hosokawa-Yashū

Father:  Hosokawa Masaharu

Mother:  Daughter of Kōno Michimasa

Siblings:  Takakuni, Harukuni, Michimasa

Wife:  Daughter of Akamatsu Urayasu

Adopted Children:  Michitada

Hosokawa Michimasa served as a bushi during the Sengoku period.  He was the sixth head of the Hosokawa-Yashū family.  Under an alternate theory, he was a fictional character.


Michimasa was born as the son of Hosokawa Masaharu.  He received one of the characters in his name from Ashikaga Yoshiteru, the thirteenth shōgun of the Muromachi bakufu, and changed his name to Terumasa.

His second oldest brother, Hosokawa Harukuni, served as the head of the Yashū family.  On 8/29 of Tenbun 5 (1536), owing to a betrayal by Miyake Kunimura who colluded with Hosokawa Harumoto, Harukuni was compelled to take his own life at the Tennō Temple in Settsu Province.  As a result, Michimasa succeeded him as the head of the Yashū family.  At this time, Michimasa inherited Bitchū Province along with the Ima and Onsen districts of Iyo Province.

On 7/3 of Tenbun 6 (1537), Michimasa sent a letter to Hosokawa Michitada (Harukuni’s son) requesting him to have Hosokawa Ujitsuna (Takakuni’s adopted son) recognize his succession to the headship of the Yashū family.  That same year, Michitada moved from Iyo-Matsuyama Castle in the Onsen District to Kawanoe Castle in the Uma District of Iyo.  There is a theory that, based on the fact that Ujitsuna adopted that name in 1543, the letter was not written in 1537 but rather in 1543 or thereafter.

In 1552, Michimasa was conferred the high-ranking title of yakatagō from Ashikaga Yoshiteru.

In 1553, Michimasa died at Matsuyama Castle at the age of fifty.  He was succeeded by his nephew, Hosokawa Michitada.

References that Harukuni and Michimasa controlled Bitchū Province appear connected to the appointment of their father, Masaharu, as the military governor of Bitchū in 1515.  Owing to battles against Shō Motosuke from 1491 to 1492, the original Hosokawa family of the military governor of Bitchū lost power.  After inheriting the Hosokawa-Keichō family, Takakuni opposed the independence of the Shō family and the influence of the Hosokawa family of the military governor of Awa (the original home of Hosokawa Sumimoto and Hosokawa Harumoto), and appointed Masaharu of the Yashū family (which had a fief in the Asakuchi District) as the military governor of Bitchū.  After the death of Masaharu, however, this came to a standstill.

Theory of a fictional character

There is a theory that Hosokawa Michimasa was a fictional character based on the following line of reasoning:  Harukuni’s birth year was established to have been in 1516.  In 1517, Masaharu fell ill and died early in 1518 so, given that there was not enough time to produce Harukuni’s younger brother, Michimasa was fabricated to enable the Chōfu-Hosokawa family (who were descendants of Hosokawa Michitada) to appear as a direct lineage of the Yashū family.  Michitada was a member of the Hosokawa family but, after the demise of Harukuni, surmised to have been promoted from a collateral branch.