The Nagao of Echigo province were a powerful clan, whose influence grew as they gradually conquered more land in Echigo province. In 1561 the main line of the Nagao clan essentially became Uesugi as Nagao Kagetora was adopted into the Uesugi clan and changed his name to Uesugi Kenshin. The remaining members of the Nagao clan who chose to keep the surname became vassals of the Uesugi clan.
The Naito clan served the Ouchi clan until the Ouchi demise in 1557 and afterwards came to serve the Mori clan.
The Nakajo of Echigo province sided with the Uesugi and they served on to fight in the 4th battle of Kanawakajima.
The Nambu of Dewa province were related to the Takeda clan. They competed with the Akita clan and other clans for territory in the north of Japan and became locally powerful in the northern part of Mutsu province.
The Naoe of Echigo province were related to the Otomo clan. They became important retainers of the Nagao clan and later the Uesugi.
The Narita held lands in Musashi province and were initially allies of the Uesugi, but switched sides to the Hojo clan. They served the Hojo in the siege of Odawara and afterwards were awarded with a fief by the Tokugawa in Shimotsuke province.
The Niiro of Satsuma province were related to the Shimazu clan and they became the principal retainers of the Shimazu.
The Niki of Iga province were a minor clan, who intially supported the Ashikaga shogunate. They tenuously held their domain into the early Sengoku period and the Niki clan of Iga province, helped by local ninja forces, at first managed to defeat forces of the Oda clan, but were finally overcome by the Oda. The ninja of Iga province were famous throughout Japan and some were hired for their services by the Tokugawa.
The Niwa of Owari province were related to the Kodama clan. They came to serve the Oda clan and rose to some prominence. The Niwa lost a great deal of their influence with the death of Oda Nobunaga, but managed to survive.
The Nomi were retainers of the Mori clan and later commanded forces under the Kobayakawa.
The Nukui were intially retainers of the Hatakeyama, but after the fall of the Hatakeyama at the hands of the Uesugi, they came to serve Oda Nobunaga.
The Obata clan were related to the Takeda clan. They shifted their allegiances between Uesugi, Nagao, Takeda and Hojo depending on the situation in Kozuke province. They entered into the service of the Tokugawa after the destruction of the Takeda clan.
The Oda clan hailed from Owari province. Prior to the Sengoku period they had originally been retainers of the Shiba clan, but when the power of the Shiba clan dwindled, the Oda became lords of Owari province. The Oda rapidly rose to power after they defeated the Imagawa at the battle of Okehazama in 1560. Although the Oda were hugely outnumbered at the battle of Okehazama, Oda Nobunaga's forces launched a surprise attack under the cover of a thunderstorm on the invading forces of the Imagawa clan, who were camping in a valley near the village of Okehazama and the Oda quickly defeated the Imagawa invasion force. The Oda allied themselves with the Tokugawa clan after the famous battle of Okehazama. Oda Nobunaga made a drive for national hegemony and he was the first to do so in the Sengoku period. A progressive leader, Oda Nobunaga became known as the first of the socalled Three Unifiers of Japan. He had many capable generals under him, many of whom would rise to great fame, such as Maeda Toshii and Toyotomi Hideyoshi. Toyotomi Hideyoshi who was of humble origins, rose to great status under Oda Nobunaga. Toyotomi Hideyoshi became known as the second of the socalled Three Unifiers of Japan (the third being Tokugawa Ieyasu), after Oda Nobunaga was murdered by Akechi Mitsuhide. The Oda clan influence dwindled after the death of Oda Nobunaga due to the betrayal of Akechi Mitsuhide.
The Ogasawara clan of Shinano province had diplomatic ties with the Imagawa clan, unfortunately for the Ogasawara these ties proved to be of no avail. The Ogasawara clan were attacked by the Takeda and were forced to flee to safety within the Uesugi domain. In the late Sengoku period the remaining Ogasawara became retainers of the Tokugawa.
The Okabe of Suruga province became retainers of the Imagawa clan. They served the Imagawa until the fall of the Imagawa in 1569 and afterwards came to serve the Takeda and ultimately became retainers of the Tokugawa.
The Okubo were related to the Utsunomiya clan and came to serve the Matsudaira clan. The clan achieved much success in the service of Tokugawa Ieyasu.
The Okudaira of Mikawa province were retainers of the Matsudaira clan and served the Matsudaira at the battle of Anegawa.
The Omura were a minor clan who settled in Hizen province. They traded with the Portuguese and clashed with pirates. The Omura were bitter rivals of the Matsuura.
The Ota had held Edo castle in Musashi province, but lost the castle to the Hojo clan and afterwards the clan largely disappeared from history.
The Otomo clan settled in Bungo province and managed to extend their influence over much of Kuyushu island. Defeats at the hands of the Shimazu clan weakened the Otomo and they were on the verge of being destroyed by the Shimazu, however Toyotomi hideyoshi invaded Kyushu island and this soon changed the Otomo fortunes.