The Ijuin were related to the Shimazu clan and served the Shimazu throughout the Sengoku period. They took part in the battle of Mimigawa and fought against the Otomo clan.
The Ikeda entered the service of the Oda and later sided with the Tokugawa. After the battle of Sekigahara they would become one of the richest Daimyo in Japan.
The Ikoma were originally from Owari province and they came to serve each of the Three Unifiers, first Oda Nobunaga, then Toyotomi Hideyoshi and finally Tokugawa Ieyasu.
The Imagawa capital was situated in Sumpu in Suruga province. The Imagawa controlled Suruga, Totomi and much of Mikawa province. They had family ties with the Hojo and were quite influential in the south of Japan. The Imagawa were defeated at the battle of Okehazama in 1560 by Oda Nobunaga and this defeat would mark their rapid decline from power and their eventual downfall. As a result of the defeat at the battle of Okehazama many of their vassals rebelled and switched sides to the Tokugawa clan. Alienated from their vassals and betrayed by the Hojo, the Imagawa clan finally succumbed to the Takeda clan in 1569. The Imagawa clan lived on to provide masters of ceremony to the Tokugawa.
The Inaba were retainers of the Saito clan, but later served the Oda clan. They took part in the battle of Anegawa and following the death of Oda Nobunaga came to serve Toyotomi Hideyoshi.
The Inoue clan came to prominence late in the Sengoku period. They settled in the Takai district in Mino province at a place called Inoue from which their name derived.
The Irobe were retainers of the Uesugi clan and fought in the 4th battle of Kawanakajima and also in the battle of Sano in Kozuke province in 1563. The Irobe were rewarded for their efforts in battle with a fief in Kozuke province.
The Ishida were intially a locally powerful clan in Omi province. They managed to defeat the Asai clan and afterwards were suspected of being involved in numerous plots and assassinations. The Ishida chose to oppose the Tokugawa, but Ishida Mitsunari was decisively defeated at the battle of Sekigahara by Tokugawa Ieyasu.
The Ishikawa were allied with the Ashina clan and were related to the Date clan. They settled in Mikawa province and came to serve the Matsudaira clan.
The Isshiki were a clan based in Tango province. They opposed Oda Nobunaga and suffered an invasion of their lands by the Hosokawa, who were acting upon orders of Oda Nobunaga. At first the Isshiki managed to resist the Hosokawa, but when the Akechi arrived, they were betrayed by their allies and subsequently surrendered.
The Ito were a powerful clan from Hyuga province. They were bitter rivals of the Shimazu and eventually lost their lands to the Shimazu. The Ito were re-established as Daimyo following the invasion of Kyushu island by Toyotomi Hideyoshi.
The Jinbo of Etchu province were vassals of the Hatakeyama clan. The Jinbo were almost constantly at war with local rivals and ultimately defeated by the Nagao. They enjoyed a brief resurgence of their power, but when Uesugi Kenshin sided with one of their rivals, they were defeated once again and at length became Uesugi vassals.
The Jo clan of Higo province were related to the Kikuchi clan. They were forced to surrender after Toyotomi Hideyoshi invaded Kyushu island and afterwards they became retainers of the Shimazu.
The Kakizaki settled in Echigo province and intially clashed with the Nagao clan, but later came to serve Uesugi Kenshin. They remained into Uesugi service over the course of the remainder of the Sengoku period.
The Kamei were retainers of the Amako clan and they fought against the mori, but came to serve Toyotomi Hideyoshi when the Amako cause died. The Kamei participated in the invasion of Kyushu and were rewarded for their service.
The Kasai clan of Mutsu province were locally powerful and clashed with the Hatakeyama clan and the Ashina clan, but later came to be allies with the Hatakeyama clan. After they clashed with the Date clan, the Kasai allied with the Date, but ultimately were attacked by their new found allies and were seriously defeated. The power of the Kasai clan waned and they were finally dispossessed by Toyotomi Hideyoshi. The Kasai rebelled under Toyotomi Hideyoshi, but were suppressed by the Date.
The Kato clan originated from the same village in Owari province as Toyotomi Hideyoshi and they also served the Oda clan. After the death of Oda Nobunaga, the Kato went on to serve Toyotomi Hideyoshi. The Kato received a fief in Higo province and were known to prosecute Christians.
The Kii clan were a minor Daimyo clan in Buzen province that was supplanted by the Otomo clan. They ultimately threw in their lot with the Shimazu clan, but without much avail.
The Kikkawa of Aki province served the Akamatsu clan and at first competed with the Mori clan for land in Aki province, but were finally brought under the sway of the Mori clan.
The Kikuchi were a powerful clan from Higo province. They fought other powerful rivals on Kyushu island, including the Shimazu clan and the Otomo clan, but were first subdued by the Ouchi clan and finally destroyed by Otomo Sorin.