The were a Japanese clan which claimed descent from Fujiwara Kaneie's son Michikane. They assumed the name Rusu following Minamoto no Yoritomo

Minamoto no Yoritomo

was the founder and the first shogun of the Kamakura Shogunate of Japan. He ruled from 1192 until 1199.-Early life and exile :Yoritomo was the third son of Minamoto no Yoshitomo, heir of the Minamoto clan, and his official wife, a daughter of Fujiwara no Suenori, who was a member of the...

's conquest of northern Japan; the family, then named Isawa, were entrusted with keeping watch in the north during Yoritomo's absence ( being the Japanese word for "absence"). In the 14th century Nanboku-chō Period, the family joined the forces of Kitabatake Akiie

Kitabatake Akiie

was a Japanese court noble, and an important supporter of the Southern Court during the Nanboku-chō Wars. He also held the posts of Commander-in-Chief of the Defense of the North, and Governor of Mutsu Province...

 and fought with distinction at Tsugaru and Shirakawa. However, in 1336, the family switched sides while on campaign in Mikawa Province

Mikawa Province

is an old province in the area that today forms the eastern half of Aichi Prefecture. It was sometimes called . Mikawa bordered on Owari, Mino, Shinano, and Tōtōmi Provinces....

, and instead fought for the northern court's side. Soon after, they also became involved in the Kan'nō War in 1351.

The Rusu family became established at Takamori Castle by the 16th century, and were supported by the Date clan. The Rusu and Date also formed kinship ties through marriage and adoption. Relations between the Rusu and Date continued to improve, and in the Edo period, the Rusu became samurai of the Date clan's Sendai Domain

Sendai Domain

was a Japanese domain of the Edo period. Most of its holdings were contiguous, covering all of modern-day Miyagi Prefecture, small portions of southern Iwate Prefecture, and a portion of northeastern Fukushima Prefecture. The domain's capital, and the ruling family's castle, were located in what...

. The Rusu family also assumed the Date surname in the Edo period, and ruled Mizusawa

Mizusawa Domain

The was a feudal domain in Mutsu Province of Japan during the Edo period. It was a subdomain of the Sendai Domain. Sometimes it was suggested that the domain be called "Naka-Tsuyama han"...

, a sub-domain of Sendai. The family ranked as , relatives of the Date lord, in the Sendai domain's retainer ranking structure.

Date Kuninori

Date Kuninori

was a Japanese samurai of the late Edo period. Kuninori was both the 12th head of the Mizusawa-Date clan and the 26th generation head of the famed Rusu clan, and served as a retainer of the Sendai domain...

, who settled Hokkaidō

Hokkaido

, formerly known as Ezo, Yezo, Yeso, or Yesso, is Japan's second largest island; it is also the largest and northernmost of Japan's 47 prefectural-level subdivisions. The Tsugaru Strait separates Hokkaido from Honshu, although the two islands are connected by the underwater railway Seikan Tunnel...

 in the early Meiji era, was a descendant of this clan.