Koichi Hirose (広瀬 康一, Hirose Kōichi) is a side character and ally featured primarily in Diamond is Unbreakable and appearing briefly in Vento Aureo.

Koichi is a meek high-school first-year who finds himself embroiled in the world of Stand users as he befriends Josuke Higashikata. Koichi also becomes a Stand User and wields Echoes.