Kasaidono (1233? - October 16, 1317?) was a female member of the Hojo clan who lived during the middle years of the Kamakura period. She was the first daughter of Shigetoki HOJO. She was the second lawful wife of Tokiyori HOJO, the fifth shikken (regent) of the Kamakura bakufu (Japanese feudal government headed by a shogun). She was the mother of Tokimune HOJO, who became the eighth shikken. Her other children included Munemasa HOJO and a daughter (who died a premature death).
Tokiyori HOJO took a daughter of Suemitsu MORI as his lawful wife when he was 13 years old, but divorced her because Suemitsu sided with the Miura clan at the Battle of Hoji. Later, he took a daughter of Shigetoki, his grandfather's brother as well as shukuro (a chief vassal of the Hojo clan), as his second lawful wife. Some researchers claim that Tokimune's mother was a daughter of Suemitsu MORI, based on the description in the "Hojo shi Keizu" (Asaba bon) (Hojo Clan's Genealogy - Asaba Version) that a daughter of Suemitsu Mori was Tokimune's mother. However, according to the veneration pledge for the construction of Tahoto Pagoda at Gokuraku-ji Temple, which was written at the 12th anniversary of Shigetoki HOJO's death, Shigetoki's daughter gave birth to and raised Tokimune, and there exist several other historical materials evidencing such description.
Though Tokiyori already had a son named Tokisuke HOJO with his concubine, he strongly wished to have an heir with his lawful wife and offered a fervent prayer for pregnancy at Tsuruoka Hachiman-gu Shrine. On May 15, 1251, Kasaidono gave birth to Tokimune at the Amanawa residence where Matsushitazenni (Zen nun of Matsushita), Tokiyori's mother, lived.
She gave birth to Munemasa on January 28, 1253, and one year later she gave birth to a girl on October 6, 1254. The girl died at the age of 3 on October 13, 1256, and Tokiyori entered into priesthood in the same year. Kasaidono was a devoted believer in Ritsu Sect of Saidai-ji Temple (Nara City) lineage, and received a strong moral impact from Zen and Ritsu Sect after she married Tokiyori.
Kasaidono lived in Kasai-dani Valley (now Komachi, Kamakura City), managed the fief owned by the Tokuso family (head of the Hojo clan) and was involved in trading with China (the Yuan Dynasty), according to the historical materials. "Kamakura Nendaiki Uragaki" (Kamakura Chronicles End Note) stated that "Kasaidono passed away at the age of 85" on October 16, 1317, which was considered to refer to Tokimune's mother.