- Sons: Yamauchi Tadayoshi
- Distinction: Yamauchi retainer
Yasutoyo was a younger son of Yamauchi Moritoyo. He assisted his elder brother Yamauchi Kazutoyo in quelling the difficult elements of Tosa province and was awarded the 20,000 koku branch domain of Nakamura. After Kazutoyo died without an heir, Yasutoyo's son Yamauchi Tadayoshi succeeded Kazutoyo as lord of Tosa han.
References
- Initial text from Sengoku Biographical Dictionary (Samurai-Archives.com) FWSeal & CEWest, 2005