After a short while, Choei got acquainted with Kazan WATANABE, a senior vassal of the Tahara Domain of Mikawa Province and was employed as a Dutch scholar at the domain for his brilliant talent, where he translated Western studies literature with Sanei KOSEKI and Shunzan SUZUKI.
まもなく三河国田原藩重役渡辺崋山と知り合い、その能力を買われて田原藩のお雇い蘭学者として小関三英や鈴木春山とともに蘭学書の翻訳に当たった。