Kyohei Rai was born in Aki Province, Hiroshima Prefecture in 1752. Kyohei Rai was a younger brother of Shunsui and uncle of Sanyo.
Manshiro became a Confucian scholar of the Aki Clan. He reformed the clan's education administration. Manshiro was good at writing both prose and poetry in Chinese. He distinguished himself as a county commissioner in his late life.