Kasai clan

A vassal of the Kamakura Shogunate and a feudal lord in the Sengoku period of Mutsu. He descended from the Kanmu Heishi clan and was based in Kasai Mikuriya, Shimousa Province (Edogawa Ward, Katsushika, Tokyo). During the reign of Kiyoshige, he served Minamoto no Yoritomo and distinguished himself in the Oshu expedition. He was appointed as the Oshu Magistrate and was given territories in Isawa, Iwai, and Oshika counties (southern Iwate Prefecture to northern Miyagi Prefecture). During the Nanboku-cho period, Kiyosada fought in various places as a member of the Kitabatake clan and was the center of the Southern Court's power in Oshu, but later he joined the Ashikaga clan. From the Muromachi period to the Sengoku period, the clan was based in Teraike Castle in Tomegun (Tome City, Miyagi Prefecture) and controlled seven districts south of Isawa, Esashi, and Kesen districts along the Kitakami River. Eventually, they were overwhelmed by the power of the Date clan, and during the Tenbun era (1532-1555), Harutane, who came from the Date clan, became the head of the family. During the time of his son, Harunobu, in 1590 (Tensho 18), Toyotomi Hideyoshi confiscated his territory for failing to attend the Siege of Odawara, and the clan was destroyed.

[Yuko Ikegami]

Source: Shogakukan Encyclopedia Nipponica About Encyclopedia Nipponica Information | Legend

鎌倉幕府御家人(ごけにん)、陸奥(むつ)の戦国大名。桓武平氏(かんむへいし)より出て、下総国(しもうさのくに)葛西御厨(みくりや)（東京都葛飾(かつしか)・江戸川区）を本拠とする。清重(きよしげ)のとき源頼朝(みなもとのよりとも)に仕えて奥州出兵に戦功をたて、奥州総奉行(そうぶぎょう)に任ぜられるとともに、胆沢(いさわ)・磐井(いわい)・牡鹿(おしか)郡（岩手県南部から宮城県北部）などに所領を与えられた。南北朝期には清貞(きよさだ)が北畠氏(きたばたけうじ)に属して各地を転戦、奥州の南朝勢力の中心であったが、のち足利氏(あしかがうじ)に属す。室町期から戦国期には登米郡(とめぐん)寺池城（宮城県登米市）に拠(よ)って、胆沢・江刺(えさし)・気仙(けせん)郡以南の北上川流域7郡を支配。やがて伊達氏(だてうじ)の勢力に押され、天文(てんぶん)年間（1532～1555）には伊達氏から入った晴胤(はるたね)が家督となる。その子晴信のとき、1590年（天正18）、小田原の陣に不参のため豊臣秀吉(とよとみひでよし)によって所領を没収され滅亡。

［池上裕子］

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