was a samurai

Samurai

is the term for the military nobility of pre-industrial Japan. According to translator William Scott Wilson: "In Chinese, the character 侍 was originally a verb meaning to wait upon or accompany a person in the upper ranks of society, and this is also true of the original term in Japanese, saburau...

commander in the Muromachi period

Muromachi period

The is a division of Japanese history running from approximately 1336 to 1573. The period marks the governance of the Muromachi or Ashikaga shogunate, which was officially established in 1338 by the first Muromachi shogun, Ashikaga Takauji, two years after the brief Kemmu restoration of imperial...

 during the 16th century of Japan.

Sumimoto was one of the few sons of Hosokawa Yoshiharu and an adopted son of Hosokawa Masamoto

Hosokawa Masamoto

a notable Deputy-Shogun of the Hosokawa clan of Japan, and son of Hosokawa Katsumoto. Masamoto was appointed to this very high rank during the year of 1486. However, for a brief period this title was lost by Hatakeyama Masanaga but was regained in time. When Ashikaga Yoshihisa died childless during...

, who was the Kanrei

Kanrei

or, more rarely, kanryō, was a high political post in feudal Japan; it is usually translated as Shogun's Deputy. After 1349, there were actually two Kanrei, the Kyoto Kanrei and the Kantō Kanrei....

 of the Ashikaga shogunate

Ashikaga shogunate

The , also known as the , was a Japanese feudal military regime, ruled by the shoguns of the Ashikaga clan.This period is also known as the Muromachi period and gets its name from Muromachi Street of Kyoto where the third shogun Ashikaga Yoshimitsu established his residence...

. His roots was the Hosokawa clan

Hosokawa clan

The ' was a Japanese samurai clan, descended from Emperor Seiwa and a branch of the Minamoto clan, by the Ashikaga clan. It produced many prominent officials in the Ashikaga shogunate's administration. In the Edo period, the Hosokawa clan was one of the largest landholding daimyo families in Japan...

 at Awa Province

Awa Province (Tokushima)

was an old province of Japan in the area that is today a part of Tokushima Prefecture on Shikoku. Awa was bordered by Tosa, Sanuki, and Iyo Provinces. It was sometimes called .-References:...

.

Masamoto did not have his own child and originally had decided to let Hosokawa Sumiyuki, who was from Kujyō clan

Kujō family

The Kujō family was a Japanese noble family and a branch of the Fujiwara clan derived from Fujiwara no Tadamichi. They were counted as one of the Sekke, the five regent houses and therefore one of the most politically powerful families among the kuge .As one of the Sekke, the five regent houses,...

, succeed the house. However, he changed his mind later and decided to let Sumimoto, who was adopted after Sumiyuki, succeed the house. This naturally caused a rift between Sumimoto and Sumiyuki.

In 1507, Masamoto was killed by an adherent of Sumiyuki. Sumimoto was attacked by a retainer of Sumiyuki, Kozai Motonaga, and escaped to Koga, Ōmi Province

Omi Province

is an old province of Japan, which today comprises Shiga Prefecture. It was one of the provinces that made up the Tōsandō circuit. It is nicknamed as .Lake Biwa, Japan's largest lake, is located at the center of the province...

, taking refuge at Rokkaku Takayori.

Following this, a powerful vassal under the Hosokawa, known as Miyoshi Yukinaga (Nagateru), raised troops in Settsu

Settsu Province

was a province of Japan, which today comprises the eastern part of Hyōgo Prefecture and the northern part of Osaka Prefecture. It was also referred to as or .Osaka and Osaka Castle were the main center of the province.-History:...

 and destroyed Sumiyuki in the young Sumimoto's name. Kicking back Sumiyuki, Sumimoto succeeded the house in a proper form.

He and Hosokawa Takakuni

Hosokawa Takakuni

Hosokawa Takakuni was the most powerful military commander in the Muromachi period under Ashikaga Yoshiharu, the twelfth shogun. His father was Hosokawa Masaharu, who was the branch of the Hosokawa clan....

, who was from a branch of Hosokawa clan and also another foster son of Masamoto, supported Ashikaga Yoshizumi

Ashikaga Yoshizumi

was the 11th shogun of the Ashikaga shogunate who reigned from 1494 to 1508 during the Muromachi period of Japan. He was the son of Ashikaga Masatomo and grandson of the sixth shogun Ashikaga Yoshinori. Yoshizumi was first called Yoshitō , then Yoshitaka.Yoshizumi was adopted by the 8th shogun...

, who was backed up to the 11th Shogun

Shogun

A was one of the hereditary military dictators of Japan from 1192 to 1867. In this period, the shoguns, or their shikken regents , were the de facto rulers of Japan though they were nominally appointed by the emperor...

 by Masamoto. In 1493, Masamoto had deposed the 10th Shogun Ashikaga Yoshiki

Ashikaga Yoshitane

, also known as Ashikaga Yoshiki , was the 10th shogun of the Ashikaga shogunate who headed the shogunate first from 1490 to 1493 and then again from 1508 to 1521 during the Muromachi period of Japan....

 (Yoshitane), who later escaped from confinement and fled to eastern countries, looking for a chance to regain his position.

In 1508, Ōuchi Yoshioki

Ouchi Yoshioki

was a samurai of the Ōuchi family who lived during Japan's early Sengoku period. He is famous for his role in restoring the Shogun Ashikaga Yoshitane to power in 1508, and in building Saijō castle....

, who then harbored Yoshiki, marched his armies into Kyoto and made Yoshiki back into the seat of Shogun. The relationship between Sumimoto and Takakuni was no longer in harmony, and while Takakuni acted in concert with Yoshioki, Sumimoto was purged to Ōmi Province. Sumimoto intended to battle against Yoshioki in the province of Settsu, but ended up fleeing to Awa after seeing the superior numbers of Yoshioki's army.

In 1511, Sumitomo returned to Kyoto

Kyoto

is a city in the central part of the island of Honshū, Japan. It has a population close to 1.5 million. Formerly the imperial capital of Japan, it is now the capital of Kyoto Prefecture, as well as a major part of the Osaka-Kobe-Kyoto metropolitan area.-History:...

 but ended up being defeated by Takakuni and the Ōuchi at Funaokayama and fled once more. The death of Yoshizumi was another shock to the camp of Sumimoto.

Ōuchi Yoshioki left the capital in 1518 to maintain his own dominion, and regarding this as a chance, Sumimoto attempted another movement to Kyoto in the next year, cooperating with Miyoshi Yukinaga. However, Yukinaga ended up being attacked and defeated by Hosokawa Takakuni and the clan of Rokkaku

Rokkaku clan

The was a Japanese samurai clan which wielded considerable power in the Muromachi period under the Ashikaga shogunate.-Rise and Fall:Founded by Sasaki Yasutsuna of Ōmi province in the 13th century, the name Rokkaku was taken from their residence within Kyoto; however, many members of this family...

, who were then at the side of Ashikaga Yoshiki. Yukinaga was caught and forced to die in seppuku

Seppuku

is a form of Japanese ritual suicide by disembowelment. Seppuku was originally reserved only for samurai. Part of the samurai bushido honor code, seppuku was either used voluntarily by samurai to die with honor rather than fall into the hands of their enemies , or as a form of capital punishment...

. Sumimoto was ill and had not advanced to Kyoto. After Yukinaga's defeat, he escaped again to his home province of Awa and died soon.