Lifespan: 14xx to 11/21 of Kyōroku 2 (1529)
Title: Assistant Director of the Bureau of Military Storehouses, Governor of Yamato
Lord: Hosokawa Masamoto → Hosokawa Sumimoto → Hosokawa Takakuni → Miyoshi Motonaga
Father: Itami Masayori
Siblings: Motosuke, Chikanaga
Wife: Daughter of Mano Tokiaki
Children: Kunisuke (?), Masakatsu (Yasunao) (?)
Itami Motosuke served as a bushō during the Sengoku period. He was a retainer of the Hosokawa clan and served as the lord of Itami Castle in Settsu Province.
Motosuke originated from the lineage of the Itami clan, kokujin, or provincial landowners, in Settsu. Initially, he served Hosokawa Masamoto, the kanrei, or deputy shōgun, of the Muromachi bakufu. At this time, he received one of the characters from the name of Masamoto and changed his name from Masaoki to Motosuke.
In the sixth month of 1507, Masamoto was assassinated in a plot by one of his three adopted sons, Hosokawa Sumiyuki, in an event known as the Lord Hosokawa Incident. His death led to internal discord regarding his successor to Hosokawa-Keichō family – the main branch of the Hosokawa clan. This branch served as hereditary military governors of Settsu, Tanba, Sanuki, and Tosa provinces in addition to the role of deputy shōgun for the Muromachi bakufu in Kyōto. In the background, the retainers of the Hosokawa-Keichō family in the Kinai were opposed to the Miyoshi clan of Awa Province who supported Hosokawa Sumimoto, another one of Masamoto’s adopted sons.
Furthermore, the former shōgun, Ashikaga Yoshitane, had designs to overthrow the current shōgun, Ashikaga Yoshizumi, and reclaim his position. Based on the support of others in the Kinai, Hosokawa Takakuni (another one of Masamoto’s adopted sons) became the successor to Masamoto one year after Masamoto’s assassination, while Yoshitane reclaimed the role of shōgun. Meanwhile, Yoshizumi and Sumimoto, along with their supporters in the Miyoshi clan, aimed to restore their authority, resulting in a prolonged series of military clashes in the Kinai known as the Conflict between the Hosokawa (Ryō-Hosokawa no ran). This conflict between two branches of the Hosokawa clan and their respective allies ran approximately from 1509 until 1531.
The Eishō Disturbance (Eishō no sakuran) refers to a succession struggle within the Hosokawa-Keichō family in combination with a competition in the Ashikaga family for the role of shōgun. The name of the disturbance derives from its occurrence during the Eishō era (1504-1521).
In the fourth month of 1508, after Takakuni invaded Kyōto, based on enmity toward Miyoshi Yukinaga, Motosuke, together with Naitō Sadamasa (the deputy military governor of Tanba Province), headed toward the capital and expelled Sumimoto and Yukinaga to Ōmi Province. In the eleventh month of 1519, Motosuke was attacked at Itami Castle by Sumimoto and Yukinaga, but, in the fifth month of 1520, after Sumimoto and Yukinaga were defeated by Takakuni at the Battle of Tōji Monastery, Motosuke reclaimed Itami Castle.
In the first month of 1527, when Hatano Motokiyo and Yanagimoto Kataharu (acting in concert with Miyoshi Katusnaga and Miyoshi Masanaga to back Sumimoto’s orphan, Hosokawa Rokurō (later known as Hosokawa Harumoto) attacked several castles in succession in Settsu Province, Motosuke resisted them from Itami Castle. In the second month of 1527, after Takakuni lost to the Miyoshi forces at the Battle of Katsurakawara, Motosuke continue to hole-up in the castle, but, in the tenth month, surrendered. Thereafter, he affiliated with Miyoshi Motonaga. In the eighth month of 1529, when Motonaga withdrew to Awa Province owing to a conflict with Yanagimoto Kataharu who was on the same side of the Miyoshi, Motosuke became isolated in the Kinai. On 11/21, Kataharu launched an assault against Itami Castle and Motosuke was killed in action.
Headship of the clan was inherited by Itami Kunisuke who is surmised to have been Motosuke’s son. In 1530, after Takakuni returned to Kyōto, Kunisuke joined and remained on his side until dying in the Collapse at Daimotsu. One other son, Itami Chiyomatsu (later known as Itami Yasunao), fled the difficulties and, after wandering to many places, later became a retainer of Imagawa Yoshimoto in Suruga Province.