was a retainer of the Japanese Hōjō clan

Late Hojo clan

The ' was one of the most powerful warrior clans in Japan in the Sengoku period and held domains primarily in the Kantō region.The clan is traditionally reckoned to be started by Ise Shinkurō, who came from a branch of the prestigious Ise clan, a family in the direct employment of the Ashikaga...

 and an early daimyo of Shimōsa Province. Harutomo was the son of Oyama Takatomo and was adopted by his uncle Yūki Masakatsu

Yuki Masakatsu

was a Japanese samurai of the Sengoku period who ruled the Yūki clan. He was the son of Yūki Masatomo. Masakatsu assumed family headship around 1525, he would then compose an official house code known as the Yūki-shi Shin Hatto , which was completed by 1556...

. Harutomo ultimately accepted the authority of the Hōjō, by his ties were severed when Toyotomi Hideyoshi

Toyotomi Hideyoshi

was a daimyo warrior, general and politician of the Sengoku period. He unified the political factions of Japan. He succeeded his former liege lord, Oda Nobunaga, and brought an end to the Sengoku period. The period of his rule is often called the Momoyama period, named after Hideyoshi's castle...

 besieged the Hōjō castle of Odawara

Odawara Castle

is a landmark in the city of Odawara in Kanagawa Prefecture, Japan.-History:Odawara was a stronghold of the Doi clan during the Kamakura period, and a fortified residence was built by their collateral branch, the Kobayakawa clan stood on the approximate site of the present castle...

. Harutomo later adopted the 2nd son of the famous Tokugawa Ieyasu

Tokugawa Ieyasu

 was the founder and first shogun of the Tokugawa shogunate of Japan , which ruled from the Battle of Sekigahara  in 1600 until the Meiji Restoration in 1868. Ieyasu seized power in 1600, received appointment as shogun in 1603, abdicated from office in 1605, but...

, Hideyasu, whom he later accompanied to the province of Echizen

Echizen Province

was an old province of Japan, which is today the northern part of Fukui Prefecture. It was sometimes called , with Etchū and Echigo Provinces.Echizen is famous for washi . A text dated AD 774 mentions the washi made in this area. Echizen-produced Washi is still the most commonly sold traditional...

following the year of 1600.