The Ouchi were a clan who originally held sway over Suo and Nagato province. Their capital was situated in Yamaguchi and the Ouchi expanded their domain into northern Kyushu island, whilst halting the advances of the Amako. Following a failed effort to reduce the power of the Amako, the Ouchi hold over their vassals began to wane and the Ouchi were finally destroyed by the Mori clan.
The Rusu of Mutsu province were retainers of the Date clan. The Rusu and the Date formed ties of kinship through marriage and adoption.
The Ryuzoji of Hizen province were retainers of the Shoni clan, until they overthrew the Shoni in 1553. The Ryuzoji were able to secure most of Hizen province, but the clan was weakened after the death of Ryuzoji Takanobu and was eventually supplanted.
The Saigo were a minor clan in Mikawa province who constructed Okazaki castle. They were defeated by Tokugawa Ieyasu in 1523 and afterwards the Saigo clan held the position of Karo in the Tokugawa clan.
The Saito were initially retainers of the Toki clan, but overthrew the Toki clan and established themselves as Daimyo of Mino province. The Saito had family ties with the Akechi, the Asai and the Oda through marriage. The Saito twice indecisively defeated the Oda in battle, however the Oda emerged victorious by the third time the Oda waged war on the Saito. Oda Nobunaga lured away many of Saito generals and the Saito also had to contend with the Asai along their border. In 1567 the Oda finally managed to capture a Saito stronghold and the Saito had to exile with the Asakura in Echizen province.
The Sakai of Mikawa province were related to the Matsudaira clan. They became one of the chief retainer families of the Tokugawa.
The Sakikabara were retainers of the Tokugawa clan. They fought at the battle of Anegawa and the siege of Odawara and were awarded with a fief in Kozuke province.
The Sakuma of Sagami province were related to the Miura clan. They later settled in Owari province and came to serve the Oda clan. They proved to be incompetent fighters and were eventually sacked by Oda Nobunaga.
The Sanada of Shinano province were vassals of the Takeda clan. They managed to capture a castle of the Uesugi clan in Kozuke province and even managed to defeat an attack at Ueda castle by Tokugawa Ieyasu.
The Sasaki also known as the Rokkaku clan were a powerful clan in Omi province, who were noted for their effective use of spies and ninja. They wielded significant power early in the Sengoku period, but their power declined after Kannonji castle was attacked during the Onin war. The Sasaki were also effective administrators and managed to eliminate a paper merchant guild in Mino province, where for a brief period they held power. In 1568 they were defeated by Oda Nobunaga and in 1570 they were decisively defeated by Shibata Katsuie and afterwards the clan served as messengers and envoys.
The Satake were a clan based in Hitachi province. They had family ties with the Utsunomiya clan through marriage. The Satake came to be known as aggressive warlords. They managed to defeat the Ashina clan, but later became allies with the Ashina to help combat Date Masamune. In 1590 they submitted to Toyotomi Hideyoshi. They supported the western army at the battle of Sekigahara and hence were forced to move to Dewa province by Tokugawa Ieyasu.
The Satomi clan of Awa province on Honshu island had a long standing feud with the Hojo clan after they had embarked on a failed campaign to capture Kamakura castle. They were forced to submit to the overlordship of Hojo Utjitsuna in 1539 and afterwards the Satomi saw battle against the Imagawa and the Takeda.
The Shiba were an influential clan who had held parts of Owari and Echizen province. They lost their holdings in Echizen province to the Asakura clan and in 1550 were overthrown by the Oda clan.
The Shibata clan served as senior retainers of the Oda and became well known for the exploits of Shibata Katsuie. The Shibata were related to the Sasaki clan.
The Shimazu were a powerful clan based at Satsuma province on Kyushu island. They fought many battles with their neighbouring rivals and the Shimazu managed to hold muych of Kyushu island in the late Sengoku period. The Shimazu remained powerful even after the invasion of Kyushu island by Toyotomi Hideyoshi.
The Shimizu were a local power in Bitchu province and joined the Mori around 1576 when the Kobayakawa pushed forward in that region. They held Takamatsu castle in Bitchu province for the Mori and after a long siege were forced to surrender to Toyotomi Hideyoshi.
The Shoni settled in Hizen province. They intially lost their domain to the Ouchi clan, but managed to regain it with help of the Otomo. In 1553 their vassal Ryuzoji rebelled and by 1559 the Shoni clan were completely destroyed.
The So clan governed Tsushima island throughout the Sengoku period. In 1587, Toyotomi Hideyoshi confirmed the So clan possession of Tsushima. In the struggles which followed the death of Toyotomi Hideyoshi, the clan sided with the Tokugawa. The So were heavily involved in trade with the Joseon Dynasty of Korea and the So also frequently took to piracy.
The Soma of Mutsu province were a reasonably powerful clan in northern Mutsu province. They clashed frequently with the Date clan and were finally defeated by the Date clan in the late Sengoku period.
The Suwa of Shinano province were a minor clan who allied themselves with other Daimyo from Shinano province in an effort to stop the advance of the Takeda. They were defeated by the Takeda clan and afterwards became Takeda vassals.