Primary

• Koichi’s Mother Mother of Koichi Hirose

Extended

• Koichi Hirose Friend of Josuke Higashikata
• Koichi Hirose Stand User of Echoes
• Koichi Hirose Former Enemy of Yukako Yamagishi
• Koichi Hirose Boyfriend of Yukako Yamagishi
• Koichi Hirose Ally of Jotaro Kujo