Saitō Fuku was from the Saitō clan, a prominent samurai house that had served for generations as deputy military governors of Mino province. She was born in Kuroi Castle of Tanba province, which is where her father's territory was then located. Tanba Province was under the overlordship of Akechi Mitsuhide, and her father, Saitō Toshimitsu, as his retaier, was enfeoffed on that territory by Mitsuhide. Her mother's father was Inaba Yoshimichi. Fuku's father joined Akechi Mitsuhide's rebellion to kill Oda Nobunaga during the Honnō-ji Incident. After Nobunaga was assassinated by Mitsuhide, the Saito and Akechi clan were defeated by Hashiba Hideyoshi during the Battle of Yamazaki. Then Fuku's father, Toshimitsu, retired to his castle; later he was caught in Omi province, near Sakamoto Castle, and was executed. It is thought that his various brothers, having become defeated and hunted warriors, wandered from place to place trying to escape the enemy. Because Fuku was a woman, she was spared execution and was raised by her maternal relative, aristocrat Sanjonishi Kinkuni. After being adopted, she received the highest education as an aristocrat of the privileged class. She learned the arts considered essential for the nobles of the Imperial court, including the arts of calligraphy, waka poetry and mixing incense. She was later adopted by her uncle, Inaba Shigemichi, and became the wife of Inaba Masanari, a retainer of Kobayakawa Hidekai During the marriage she had three sons, including Inaba Masakatsu, and an adopted son, Hotta Masatoshi. In 1600, during the Sekigahara campaign, Fuku's husband, Inaba Masanari, served Hideaki in the Western army led by Ishida Mitsunari. Due to the tensions Hideaki had with Mitsunari and the progression of the war being favorable to the Eastern army led by Tokugawa Ieyasu, it is said that Fuku and Masanari achieved the great feat of making Hideaki change sides and join the Eastern army. After Hideaki joined Ieyasu, Mitsunari's army was defeated, as a result of which the Fuku family obtained a large amount of spoils of war. After that, she took the step of divorcing her husband Masanari to become a wet nurse in the shogunal family and, in 1604, was formally appointed as the wet nurse of Takechiyo, the legitimate son and heir of the second shogun, Tokugawa Hidetada. She was recommended to Tokugawa Ieyasu by Itakura Katsushige for the position of wet nurse for Tokugawa Iemitsu, but there is a theory that Ieyasu chose her on his own. They say that Fuku's excellent pedigree, refined and aristocratic education and the military exploits of her ex-husband Masanari were all positive factors in her selection as a wet nurse. She was chosen for the job as a payment because she helped persuade Kobayakawa Hideaki to join the Eastern Army in the Battle of Sekigahara. She also established the Ōoku, the women's quarters, at Edo Castle. In 1607 after Iemitsu became shōgun, she became Jōrō Otoshiyori or the senior ladyship, recommended by the first Midaidokoro, Oeyo. Jōrō Otoshiyori influence was equivalent to a Rōjū in Edo Castle. In 1629, Ofuku traveled to the capital, where she had an audience with the Empress Meisho and Emperor Go-Mizunoo at the Imperial Court in Kyoto. She was promoted to the extraordinarily high Court rank of second class; and after this time, she was called Kasuga-no-Tsubone or Lady Kasuga. She had a fortune equivalent to over 100,000 koku.
Graves
Her grave is in Rinshō-in, a temple in Bunkyō, Tokyo; the temple possesses a portrait of Kasuga by Kanō Tan'yū. The Kasuga neighborhood of Bunkyō takes its name from her. Another grave is in Odawara, Kanagawa Prefecture. Kasuga no Tsubone was of a comparable court rank position to Hojo Masako and Taira no Tokiko, being one of the most prominent figures of their time.
