
Yamauchi Kazutoyo (also spelled Yamanouchi; 1545/1546? – November 1, 1605) was a prominent samurai and retainer who served Oda Nobunaga and later Toyotomi Hideyoshi during Japan's Sengoku and Azuchi-Momoyama periods. His father, Yamauchi Moritoyo, was a descendant of Fujiwara no Hidesato and a senior retainer of the Iwakura Oda clan, which opposed Oda Nobunaga. Moritoyo was also the lord of Kuroda Castle in Owari Province. Kazutoyo is especially renowned for his marriage to Yamauchi Chiyo, whose wisdom and resourcefulness played a key role in his rise to prominence.
Early Life and Service
Kazutoyo began his career as a 400-koku samurai and gained recognition as a capable leader and mentor. Notable figures such as Kuroda Nagamasa, who was a hostage of Oda Nobunaga, and Toyotomi Hidetsugu were entrusted to him for guidance. He fought on the Oda side in the Battle of Anegawa in 1570, showcasing his loyalty and martial prowess.
Rise to Power
After the Siege of Odawara in 1590, Toyotomi Hideyoshi rose to power, and Kazutoyo was granted control of Kakegawa Castle. During this period, Tokugawa Ieyasu was relocated from the Tōkai region to the Kantō region, consolidating power under Hideyoshi's regime.
The Battle of Sekigahara and Tosa Domain
Kazutoyo sided with Tokugawa Ieyasu during the pivotal Battle of Sekigahara in 1600, a victory that solidified the Tokugawa shogunate. Following the battle, Kazutoyo was rewarded with the province of Tosa, where he constructed Kochi Castle and was granted the title *Tosa no kami*. This marked the pinnacle of his career, as he transitioned from a minor samurai to the lord of an entire province.
Later Life and Legacy
Kazutoyo passed away in 1605, just four years after becoming the Lord of Tosa. He died without direct heirs and was succeeded by his nephew, Tadayoshi. Despite his relatively short tenure as a provincial lord, Kazutoyo’s legacy is intertwined with his wife Chiyo, whose strategic insight and unwavering support were instrumental in his success.
Cultural Depiction
Kazutoyo’s life and his marriage to Chiyo inspired the 45th NHK Taiga drama, "Komyo ga Tsuji" (2006). The series, based on a story by Shiba Ryotaro, portrays Chiyo as the central character and highlights her pivotal role in Kazutoyo’s rise. Nakama Yukie starred as Chiyo, with Takaya Kamikawa portraying Kazutoyo. The drama captured the couple’s journey from modest beginnings to ruling the Tosa domain, emphasizing themes of loyalty, perseverance, and partnership.
See also
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Ouchi Yoshioki

Ouchi Yoshioki, the ruler of the provinces of Suo, Nagato, and Iwami, was one of the most capable military commanders and politicians of the late 15th and early 16th centuries. The son of Ouchi Masahiro, he governed from his residence in Yamaguchi in the province of Suo. In 1499, Yoshioki gave refuge to Shogun Ashikaga Yoshitane, who had been driven out of Kyoto by Hosokawa Masamoto. Shogun Yoshizumi, Masamoto’s protégé, ordered the lords of Kyushu to unite their forces against Yoshioki; however, they did not dare to do so, fearing the power of a man who by that time controlled six provinces. Having gathered a substantial army, Yoshioki marched from his native Suo toward Kyoto in order to restore Shogun Yoshitane to power.
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Otomo Sorin

Ōtomo Yoshishige came from a noble lineage, being the eldest son of Ōtomo Yoshiaki, the ruler of Funai Province. The roots of the Ōtomo family traced back to Fujiwara Hidesato, the adopted son of Nakahara Chikayoshi. Fujiwara served Minamoto Yoritomo during the Genpei War and took part in battles in Mutsu Province in 1189. In 1193, he was appointed shugo of Buzen and Bungo Provinces, after which he adopted a new surname—Ōtomo.
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Okudaira Sadamasa

Sadamasa was the son of Okudaira Sadayoshi and took part in several battles under Tokugawa Ieyasu, distinguishing himself in the Battle of Anegawa in 1570, where he took two heads. Around 1572 he was forced to enter the service of the Takeda clan, but after the death of Takeda Shingen in 1573 he returned to Tokugawa, leaving Tsukude Castle together with his men. As a result of this defection, Takeda Katsuyori ordered the execution of Sadamasa’s wife and brother, who were being held as hostages.
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Okubo Tadatika

Tadatika, the son of Okubo Tadayō, entered the service of Tokugawa Ieyasu at the age of eleven, and took his first head in battle when he was sixteen. After the establishment of the Tokugawa shogunate, he was appointed as a rōjū — a senior bakufu official — and was regarded as one of Ieyasu’s most trusted advisors, alongside Honda Masanobu. He is also known for his military chronicle Mikawa Monogatari, which describes Ieyasu’s rise to power and the early years of the Tokugawa shogunate.
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Okubo Nagayasu

Nagayasu was the second son of Okura Nobuyasu, a sarugaku theater actor from the Takeda clan. Takeda Shingen recognized the young man’s potential and took him into service, appointing him as a vassal to his general, Tsuchiya Masatsugu. During this period, Nagayasu changed his family name to Tsuchiya. He was entrusted with developing the Takeda clan’s gold mines as well as handling matters related to taxation.
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Nitta Yoshisada

Nitta Yoshisada was a loyal soldier of Emperor Go-Daigo, who in the 1330s attempted to restore direct imperial rule in Japan. The Nitta family was related to the Ashikaga house and was older in lineage. However, they did not join Minamoto Yoritomo at the start of his war with the Taira, as the Ashikaga did, and therefore did not receive high positions in the Kamakura shogunate. This may have been one of the reasons why Yoshisada rose against the Hōjō clan in 1333.
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Natsume Yoshinobu

Yoshinobu, a long-time vassal of the Matsudaira and Tokugawa clans, governed Hamamatsu Castle on behalf of the Tokugawa house. During the clashes between the Imagawa, Takeda, and Matsudaira clans, he served in the garrison of Nagasawa Castle and in 1562 took part in raids under the command of Itakura Shigezane. When, in 1563, a revolt of the Sōtō-shū sect followers broke out in Mikawa Province, Yoshinobu joined the rebels together with Honda Masanobu and Hachiya Sadatsugu.
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Nambu Nobunao

The Nambu clan was an ancient and powerful family that traced its lineage back to the Minamoto shoguns and had controlled a significant part of the Tohoku region in northern Honshu since the 12th century. Nobunao was born in Ikatai Castle, located in what is now the city of Iwate. He was the second son of Ishikawa (Nambu) Takanobu, the 22nd head of the Nambu clan. In 1565, Nobunao’s uncle, Nambu Harumasa, adopted him, brought him to Sannohe Castle, and named him his heir, later giving his daughter in marriage to him.
