was a top-ranking official in Japan's Tokugawa shogunate

Tokugawa shogunate

The Tokugawa shogunate, also known as the and the , was a feudal regime of Japan established by Tokugawa Ieyasu and ruled by the shoguns of the Tokugawa family. This period is known as the Edo period and gets its name from the capital city, Edo, which is now called Tokyo, after the name was...

 during its early decades, and one of the chief advisors to the second Tokugawa shogun, Hidetada

Tokugawa Hidetada

was the second shogun of the Tokugawa dynasty, who ruled from 1605 until his abdication in 1623. He was the third son of Tokugawa Ieyasu, the first shogun of the Tokugawa shogunate.-Early life :...

.

The adopted son of Doi Toshimasa, Toshikatsu is generally believed to be the biological son of Mizuno Nobutomo, though there are some who claim he was an illegitimate son of shogun 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...

. He served the shogunate as advisor to shogun Tokugawa Hidetada for many years, and played an important role in communicating and overseeing the enforcement of shogunal policy across the country; Doi also helped effect trade and diplomatic relations between Japan and the Thai Kingdom of Ayutthaya

Ayutthaya kingdom

Ayutthaya was a Siamese kingdom that existed from 1350 to 1767. Ayutthaya was friendly towards foreign traders, including the Chinese, Vietnamese , Indians, Japanese and Persians, and later the Portuguese, Spanish, Dutch and French, permitting them to set up villages outside the walls of the...

. He lost much of his influence and power upon Hidetada's death in 1632. Six years later, however, Doi became one of the first to be appointed to the newly created post of Tairō

Tairo

Tairō was a high-ranking official position in the bakuhan taisei government of Japan. The tairō would preside over the governing Rōjū council in the event of an emergency. A tairō would be nominated from among a group of samurai families who supported Tokugawa Ieyasu...

(Great Elder), and was made daimyo (feudal lord) of Koga Domain

Koga Domain

The ' was a Japanese domain of the Edo period, located in Shimōsa Province . The first lord of Koga was Ogasawara Hidemasa, who was granted it as a fief following Tokugawa Ieyasu's move to the Kantō region.-List of lords:...

 in Shimousa Province

Shimousa Province

was a province of Japan in the area modern Chiba Prefecture, and Ibaraki Prefecture. It lies to the north of the Bōsō Peninsula , whose name takes its first kanji from the name of Awa Province and its second from Kazusa and Shimōsa Provinces. Its abbreviated form name was or .Shimōsa is...

, with a revenue of 160,000 koku

Koku

The is a Japanese unit of volume, equal to ten cubic shaku. In this definition, 3.5937 koku equal one cubic metre, i.e. 1 koku is approximately 278.3 litres. The koku was originally defined as a quantity of rice, historically defined as enough rice to feed one person for one year...

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See also

• Doi clan

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