Naitō Nobunari

Who They Were

Naitō Nobunari (内藤信成) was a samurai and daimyo of Ōmi Province who lived from June 13, 1545, to August 20, 1612. He served the Tokugawa clan through the Sengoku period and into the early Edo period, eventually holding a 50,000 koku fief at Nagahama in Ōmi Province.

Nobunari is believed to have been the illegitimate son of Matsudaira Hirotada, which would make him the half-brother of Tokugawa Ieyasu. He was later adopted by Naitō Kiyonaga. For much of his early career, he acted as a page to his half-brother, but his standing rose after he supported Tokugawa forces in the 1565 assault against Mikawa monk rioters.

Life and Career

Nobunari's early service was marked by loyalty to the Tokugawa cause. After distinguishing himself in the 1565 action against Mikawa monk rioters, he later fought in an assault upon Kuroma Castle, where he again proved his ability in battle.

In 1572, during the Takeda clan campaign in Mikawa, Nobunari joined Tokugawa forces. Ieyasu sent him, Honda Tadakatsu, and Ōkubo Tadasuke to lead the vanguard. They met Takeda forces led by Yamagata Masakage and Baba Nobuharu at the battle of Hitokotosaka. In that battle, Honda Tadakatsu gained recognition from enemy forces for his antler helmet and his Tonbo-giri spear, staving off charges from Baba Nobuharu's units. Nobunari and Tadakatsu both fought well, breaking through encirclement attempts by Takeda forces and leading the Tokugawa troops to escape safely.

In 1573, Nobunari supported the Tokugawa at the Battle of Mikatagahara, and in 1575 at the Battle of Nagashino. He showed at least moderate ability on both battlefields.

By 1590, Nobunari was awarded Nirayama Castle in Izu Province, holding 10,000 koku. He entered the Edo period with a 50,000 koku fief at Nagahama within Ōmi Province, where he remained as daimyo until his death in 1612.

During the Battle of Sekigahara in 1600, Nobunari defended Mimabashi Castle in Numazu, Suruga Province. Just before the battle, when Ieyasu stopped by Numazu, Nobunari expressed a wish to serve alongside Ieyasu instead of defending the castle. Ieyasu told him the importance of defending the castle, and Nobunari remained at his post.

Why They Matter

Nobunari's significance lies in his dual role as a trusted Tokugawa retainer and a regional lord. His half-brother Ieyasu relied on him in critical battles—Hitokotosaka, Mikatagahara, and Nagashino—where he helped hold the line during the Takeda campaigns. His promotion from a 10,000 koku holding at Nirayama Castle to a 50,000 koku fief at Nagahama reflects the Tokugawa reward system for loyal service.

His defense of Mimabashi Castle at Numazu during the Sekigahara campaign shows the kind of trust Ieyasu placed in him. Ieyasu's refusal to let Nobunari join the main army was not a slight; it was an assignment of strategic importance. Nobunari's willingness to ask, and his acceptance of the order, illustrates the relationship between the Tokugawa house head and his retainers.

The Name in Japanese

The name is 内藤信成, read in kana as ないとう のぶなり, and in romaji as Naitō Nobunari.

Character by character:

• 内 (ない, nai) — "inside" or "within." This is the first character of the family name Naitō. In this compound it contributes the sense of "inner," though the name as a whole is a hereditary surname and is not read for its literal meaning.
• 藤 (とう, tō) — "wisteria." This character is extremely common in Japanese surnames, often indicating descent from the Fujiwara clan (藤原, Fujiwara, literally "wisteria field"). The combination 内藤 (Naitō) is a well-established surname with roots in the warrior class.
• 信 (のぶ, nobu) — "trust," "faith," or "believe." This is the first character of the given name. It is a frequent element in samurai names, often passed down through generations or chosen to reflect a virtue. The same character appears in the name of Nobunari's father, Matsudaira Hirotada's son Ieyasu's original name, Matsudaira Takechiyo, though in different readings.
• 成 (なり, nari) — "become," "achieve," or "accomplish." This character completes the given name. Together, 信成 (Nobunari) carries the sense of "one who achieves through trust" or "faithfulness realized." The reading なり (nari) is the classical Japanese verb form meaning "to become," which gives the name a slightly archaic, formal tone.

The full name, then, is a compound of a common warrior surname and a given name built from two virtue characters. In formal contexts, the family name comes first, as in all Japanese names.

Legacy

Nobunari's legacy is preserved in the Edo period painting that depicts him as one of the Tokugawa 28 generals (Tokugawa nijūhachishinshōjin). This grouping of twenty-eight retainers was a standard subject in Tokugawa-era art, celebrating the men who helped Ieyasu rise to power. Being included in this set placed Nobunari among the most honored Tokugawa vassals.

His son, Naitō Nobumasa, continued the family line. The Naitō family, through Nobunari's service and the holdings he accumulated, remained a daimyo house into the Edo period. The 50,000 koku fief at Nagahama in Ōmi Province, which he held until his death in 1612, was the foundation of that continued status.

Nobunari's career also illustrates a pattern common among Tokugawa retainers: the illegitimate son of a minor lord, adopted into another family, rising through battlefield service to become a daimyo in his own right. His path from page to castle defender to provincial lord mirrors the broader transformation of the samurai class from the chaos of the Sengoku period to the structured hierarchy of the Edo period.