After returning to Japan, HOSHI became the first lawyer under the Ministry of Justice and actively worked in Japan, and in 1881, he became a councilor (as parliamentarian) of the Liberal Party, and took part in building the foundation of party government.
帰国後は国内で司法省付属代言人（弁護士）の第1号となって活躍し、明治14年（1881年）には自由党(明治)の議員（代議士）となり、政党政治の基礎作りの一翼を担った。