>>531020109
She's like the boss of Cerberus, Orthrus, Mino and Amy. They all work in the Underworld and the real boss from that place is Hades, but Charon is the one that makes sure that nobody slacks off (she's especially strict with Cerberus, as she tends to skip work) and that everything is working right.
Apollo also seems to be working alongside the girls, but I don't know why. I still haven't tried to read the first event where he and Mino first appear.