Ermes Costello (エルメェス・コステロ Erumēsu Kosutero), is the deuteragonist featured in Stone Ocean. Ermes is a woman voluntarily imprisoned in Green Dolphin Street Prison in order to seek revenge for her sister Gloria Costello's killer, Sports Maxx, and soon allies herself with Jolyne Cujoh in the hostile environment that the jail is. Thanks to a certain pendant, Ermes acquires a Stand, Kiss.