Yukichi lived in the house of Monojiro YAMAMOTO, who was an expert of gunnery and a public servant of Nagasaki, and learned the Dutch language under a Dutch translator, who worked as a Nagasaki official for interpreting and the like.
長崎の役人で砲術家の山本物次郎宅に居候し、オランダ通詞（通訳などを仕事とする長崎の役人）のもとへ通ってオランダ語を学んだ。