Koichi is a timid high-school first-year who befriends Josuke Higashikata and then finds himself entangled in the world of Stand users.

Koichi also becomes a Stand User and wields Echoes.

"Hey there, I am Koichi Hirose, but you can just call me Koichi. I am a first-year high schooler. I used to be an ordinary boy until one day I got hit by an arrow that turned me into a stand user weilding the Stand called Echoes."