Lifespan: 15xx to 8/19 of Keichō 17 (1612)
Other Names: Reishōin-dono, Reisanin-dono (real name is unknown)
Clan: Imagawa → Takeda → Imagawa
Father: Imagawa Yoshimoto
Husband: Takeda Yoshinobu
Reishōin was a woman who lived from the Sengoku to early Edo periods.
Reishōin was the daughter of Imagawa Yoshimoto, the eleventh head of the Imagawa clan and sengoku daimyō of Suruga Province and his formal wife, Jōkei-in. In connection with the three-party alliance between the Takeda of Kai, the Hōjō of Sagami, and the Imagawa of Suruga known as the kōsōsun-sangoku-dōmei (also known as the Zentoku Temple Alliance), Reishōin entered into a political marriage with Takeda Yoshinobu, the eldest son and designated heir of Takeda Shingen, the nineteenth head of the Kai-Takeda clan.
Reishōin’s mother, Jōkei-in, was the daughter of Takeda Nobutora (the older sister of Takeda Shingen). Jōkei-in wed Yoshimoto in 1538, reinforcing the political alliance with the Takeda of Kai but invited the scorn of Hōjō Ujitsuna of Sagami Province. A longtime rival of the Takeda clan, Ujitsuna was the second lord of the Gohōjō clan with the status of a sengoku daimyō. Ujitsuna responded by invading Suruga, burning the area near Okitsu, marking the start of the Katō Conflict. Jōkei-in died on 6/2 of Tenbun 19 (1550). To maintain the strengthen the alliance between the Takeda and the Imagawa, Reishōin was received by Yoshinobu as his formal wife. Together, they had one daughter named Enkōin.
On 11/22 of Tenbun 21 (1552), Reishōin departed from Sunpu and headed toward Kai Province. On 11/27, she married Yoshinobu when he was fifteen years old, and the Tsutsuji-ga-saki residence was newly constructed for the young couple in Kōfu. A retainer of the Takeda named Komai Kōhakusai (Masatake) accompanying the messenger to meet them noted in his diary that a bridal procession departed from Sunpu. Thereafter, in the first month of 1553, Shingen’s daughter, Kōbai-in, wed Hōjō Ujimasa, the eldest son of Hōjō Ujiyasu, the third head of the Gohōjō clan and sengoku daimyō of Sagami Province. In the seventh month of 1554, Ujiyasu’s daughter, Hayakawa-dono, wed Yoshimoto’s eldest son, Imagawa Ujizane (Reishōin’s older brother). As a result, the marriage between Reishōin and Yoshinobu served as a link in the three-party alliance between the Takeda, the Imagawa, and the Hōjō.
In 1560, after Imagawa Yoshimoto was killed by Oda forces at the Battle of Okehazama, Takeda Shingen began planning for an offensive to capture the territory of the Imagawa. Meanwhile, based on a desire to preserve the alliance with the Imagawa, Yoshinobu secretly formed a faction within the Takeda family opposed to his father in an event known as the Yoshinobu Incident. Informants notified Shingen of the plot, whereupon Yoshinobu was incarcerated in the Tōkō Temple and his band of retainers purged. It is surmised the Reishōin was forced to separate from Yoshinobu at this time, but she remained in Kōfu.
On 10/19 of Eiroku 10 (1567), Yoshinobu either took his own life or died of illness at the Tōkō Temple. In the eleventh month, Reishōin, upon demand of her older brother, Imagawa Ujizane, was returned to the Imagawa family in Suruga. Accompanied by her daughter, Enkōin, after returning to Suruga, Reishōin entered the priesthood. In the twelfth month of 1568, Takeda Shingen launched the Invasion of Suruga, leading to the end of the Imagawa as a sengoku daimyō family. Details regarding the remainder of her life are unknown.
Based on the genealogical records of the Imagawa family, after returning to Suruga, Reishōin cut her hair and adopted the name of Teishun-ni. She died on 8/19 of Keichō 17 (1612) and was buried at the Banshō Temple affiliated with the Imagawa family in Ichigaya in Edo.