The Ii clan (井伊氏)

The Ii clan was a master's house of the Hikone Domain in Omi Province.

Origin of the Ii clan, a kinsei (early modern) daimyo (Japanese feudal lord)

The Ii clan claimed that they were descendants of the Fujiwara clan
It is transmitted that the clan was established when Tomoyasu II, an adopted child of Totomi kokushu (daimyo of Totomi) FUJIWARA no Tomosuke, who was the sixth grandchild of FUJIWARA no Fuyutsugu, moved to the land of Iinoya. One theory holds that they had the family name of Mikuni, and its origin is not clear. The Ii clan governed the Iinoyanosyo for approximately 500 years during the Middle Ages, and during the period of the Northern and Southern Courts (Japan), the Ii clan belonged to the Southern Court. In the early-modern times, the Ii clan became a master's house of the Hikone Domain in Omi Province.

During the period of the Northern and Southern Courts, the Ii clan was in rivalry with Suruga no kuni shugo (provincial constable of Suruga Province) Imagawa clan, but eventually, the Ii clan was put under the control of the Imagawa clan after the Imagawa clan was appointed to the position of shugo of Totomi Province. However, the relationship between the Ii clan and the Imagawa clan who was the Shugo was a delicate one throughout the Sengoku period in Japan. When Yoshimoto IMAGAWA was defeated by Nobunaga ODA of Owari Province in the Battle of Okehazama, Naomori II followed the Imagawa clan side and was killed in the battle. Then, Naochika II was killed by Ujizane IMAGAWA because of an accusation to have planned the rebellious acts, soon after the war was over.

During the period of "Onshu Sakuran (Disturbance)," when the Ii clan lost many of their families, Naotora II who was the daughter of Naomori became a successor. Still, the Ii clan significantly lost their power, lost their castle and shoryo (territory) in Iinoya due in some part to embezzlements by vassals and the invasion of Shingen TAKEDA.

Kinsei (early modern) daimyo, the Ii clan

In 1575, a bereaved child of Naochika, Naomasa II (later, he became one of Tokugawa-shitenno [four generals serving Tokugawa Ieyasu]) left Naotora, who was raising him as his foster mother, and relied on Ieyasu TOKUGAWA who conquered the Imagawa clan. After Naomasa II succeeded in several military exploits, he accompanied Ieyasu when Ieyasu entered the Kanto area in 1590, and was given the Minowa-jo Castle in Kozuke Province with 120, 000 koku (approximately 21.6 million liters of crop yield). Naomasa was given Sawayama-jo Castle in the Omi Province with 180, 000 koku (approximately 32.4 million liters of crop yield) following the Battle of Sekigahara. After Naomasa's death, his child, Naokatsu II moved to Hikone, Omi Province in 1604 and built a castle. In 1615, however, Naokatsu handed over his position as the lord of the Hikone domain to his younger brother Naotaka Ii by the order of the bakufu (Japanese feudal government headed by a shogun). During Naotaka's day, he become a fudai daimyo (a daimyo in hereditary vassal to the Tokugawa family) with 35, 000 koku (approximately 63 million liters of crop yield). In addition, Naokatsu had succeeded Hyobu shoyu, his late father's official name of a government office, and became the lord of the Annaka Domain with 30, 000 koku (approximately 5.4 million liters of crop yield).

The head family, Ii Kamonnokami family
During the Edo period, the Hikone domain family became the top fudai daimyo family producing five Tairo (chief ministers) in six terms: Naozumi II, Naooki II, Naohide II, Naohide II, Naoaki II, and Naosuke II, among which Naomori assumed the position twice. There is controversy as to whether Naotaka assumed the Tairo position or not. In addition, the Hikone Domain family never changed their territory while other powerful fudai daimyos such as Hotta clan, Sakai clan, and Honda clan continuously changed their territories.

Because Hikone-jo Castle was too large for a daimyo with 35, 000 koku, the Bakufu ordered other daimyos for tetsudai bushin (a large-scale engineering work by federal lords under shogun's order) to build the castle. It was extremely exceptional for the Bakufu to order daimyos to build a castle for another daimyo, and it is said that the castle had a purpose to protect against Kyoto and Osaka.

At the end of the Edo period, Naosuke became a Tairo after a Roju (senior councillor of the Tokugawa shogunate) Masahiro ABE's death, and as to the issue of the successor to the Shogun, he supported the Nanki group (a group supporting Yoshitomi from the Kishu-Tokugawa family). Naosuke enforced the Ansei no Taigoku (a suppression of extremists by the Shogunate) to suppress the Hitotsubashi group (a group supporting Yoshinobu from the Hitotsubashi-Tokugawa family) and other opposition groups, but he was assassinated in the Sakuradamongai Incident. After Naosuke's death, the Bakufu placed the responsibility for this disturbance and confusion in their administration upon Naosuke, and confiscated 100, 000 koku (approximately 18 million liters of crop yield) from the Ii family. Although the Ii clan was fudai hitto (top of fudai), they changed the opinions within the clan and supported the new government after Taisei Hokan (transfer of power back to the Emperor). They belonged to the new government's side in the Battle of Toba-Fushimi, and also participated in the Boshin Civil War which followed. In 1884, the Ii family was appointed to Counts' status, and was elevated to the peerage. Naoyoshi II, one of the twin grandchildren of Naonori II who was the last lord of the Hikone domain, served as mayor of Hikone City that was a former territory of the Ii Family for nine terms since 1953.

A branch family, Ii Hyobushoyu family
The eldest son of Naomasa II, Naokatsu was said to have been an unhealthy and sickly person. The family line being established by Naokatsu, changed their territory from the Annaka Domain to the Nishio Domain, and then the Kakegawa Domain. The great-grandchild of Naokatsu and the lord of Kakegawa Domain during this period, Naotomo II, had a mental illness; this resulted in the Ii family's' Kaieki (forfeiture in rank of Samurai and properties).

However, the Ii Hyobushoyu family was allowed to adopt Naonori II, the fourth son of Naooki II from the Ii Kamonnokami family as the fifth head to restore and keep the family name. Naonori II became lord of the Yoita Domain with 20,000 koku (approximately 3.6 million liters of crop yield) without a castle. Later the tenth head of the Ii family, Naoakira II became wakadoshiyori (junior councilor). This had a direct effect upon Naoakira's promotion as joshu daimyo (daimyo who is allowed to live in a castle). After the Meiji Restoration, the family became a viscount being raised to the peerage.