Born a son of the second shogun Tokugawa Hidetada, but because of his mother's status and other circumstances he was raised in secret, cared for by Kenshōin, a daughter of Takeda Shingen.
He was adopted by Hoshina Masamitsu, lord of Takatō in Shinano.
On his adoptive father's death he became lord of Takatō. His half-brother, the third shogun Iemitsu, learning he was his brother, came to trust him deeply.
He became lord of Aizu in Mutsu, worth 230,000 koku.
Before dying, Iemitsu asked him to support the young fourth shogun Ietsuna. Masayuki allowed heirless daimyō to adopt on their deathbeds, curbing the growth of masterless samurai.
To secure drinking water for Edo's people he promoted the construction of the Tamagawa aqueduct.
In Aizu he set up community granaries to store rice against famine, and governed with care for the people, such as giving rice to the elderly.
A great fire burned most of Edo. He chose not to rebuild Edo castle's keep and spent the money on restoring the city instead.
He pressed for the ban on junshi, retainers following their lord in death.
He laid down fifteen house precepts for Aizu. Stressing loyalty to the shogunal family, they deeply shaped Aizu's conduct at the end of the Edo period.
He died in Edo, remembered as a wise ruler who helped shift shogunate government from force toward learning and law.
Takeda ShingenTokugawa HidetadaShibukawa HarumiTokugawa Ietsuna
Matsudaira NobutsunaSenhimeTokugawa IemitsuNakae TōjuNonaka KenzanKawamura ZuikenKumazawa BanzanAmakusa Shirō
People of the Edo period ・ People by period
Based on facts found in textbooks and biographies. Uncertain points are marked as such.