Lifespan: Eiroku 3 (1560) to 4/25 of Genna 4 (1618)
Title: sakon taifu (self-appointed meaning Master of the Imperial Guards of the Left Division)
Clan: Mukai (later changed to Kotakari) → Anekōji
Father: Anekōji Takatsuna
Mother: (from Hitachi Province with connections to the Satake clan)
Siblings: Nobumasa, Toshimasa
Wife: Daughter of Anekōji Yoritsuna
Children: Masatsugu, Shigemasa, two daughters
Mukai Nobumasa served as a bushō from the Sengoku to early Edo periods. In the Edo period, Nobumasa served as the chief retainer of the Dewa-Kubota domain. He founded the Mukai clan (later known as the Kotakari) with the family status of veteran retainers.
In 1560, Nobumasa was born as the son of Anekōji Takatsuna. Nobumasa is regarded to have been a member of the Mukai clan, one of three branches of the Anekōji family of Hida Province, namely, the Mukai, the Kojima, and the Furukawa.
Initially, he resided in Kotakari Castle in Hida. After the death of his father, he inherited the headship of the clan and became lord of the castle whereupon he adopted the name of Anekōji Nobumasa.
Owing to Nobumasa’s youth at the time of succession, his guardian, Ushimaru Shigechika, attempted to take control of the castle and Nobumasa was able to escape through the assistance of a retainer named Gotō Shigemoto.
During the Tenshō era (1573 to 1593), Nobumasa served Satake Yoshinobu, a sengoku daimyō in Hitachi Province, the home province of Nobumasa’s mother. Nobumasa’s younger brother, Toshimasa, also served with a stipend of 300 koku.
After the Battle of Sekigahara in the ninth month of 1600, Yoshinobu was transferred from Hitachi to the Dewa-Kubota domain. Nobumasa accompanied him to Dewa, becoming the chamberlain of Yokote Castle with a fief of 2,000 koku.
In 1603, Nobumasa was ordered to serve as a trainer below Kubota Castle and, later, became a chief retainer.
He died in 1618.
Nobumasa was the second son of Mitsuki Mayori and initially adopted the name of Kotakari Masamune. At the Battle of Komaki-Nagakute, he supported Tokugawa Ieyasu so was displaced by Kanamori Nagachika under orders of Toyotomi HIdeyoshi. He became a rōnin, or wandering samurai, and later served the Satake clan of Hitachi Province.
The betrayal by his guardian, Ushimaru Shigechika, resulted in a precarious situation for Nobumasa. Although Gotō Shigemoto detected the threat and rescued him, Nobumasa was pursued to the village of Kadokawa in the Kotakari township in the Yoshiki District. Valiant fighting by Shigemoto enabled Nobumasa to escape where he went to the Hitachi-Satake clan with connections to his mother.
In the tenth month of 1602, Nobumasa served as the chamberlain in charge of the rear gate to Yokote Castle. The next year, he moved to Akita and served as a chief retainer with a stipend of 2,400 koku. At the Tōun Temple on Mount Kessaku, there is a sub-temple founded by Nobumasa.
In the beginning, he was assigned to the band of retainers of the Yokote bushi.
He was also deeply engaged in civil affairs including the conversion of natural fields to croplands.
Nobumasa’s eldest son, Masatsugu (Seibei) wed the third daughter of Ishizuka Yoshitoki, a member of the Satake clan. Masatsugu, however, preceded his father in death so Nobumasa’s second son, Shigemasa, inherited the headship of the clan. Thereafter, he was followed by Hiromasa and Morimasa (Shōkurō) constituting the only family to continue the bloodline of the Hida-Anekōji. Nobumasa’s younger brother, Toshimasa, formed a cadet family, but it ended without an heir after one generation. The Mukai (Kotakari) family produced six chief retainers until the end of the Edo period, carrying a reputation as an esteemed family. The Mukai family presently residing in Yokote (with a surname written with a different character but the same pronunciation as Nobumasa’s surname) is a branch of the original Mukai.