Five below (Nico Di Angelos sister)

Isa di Angelo has spent her whole life living in the underworld as the daughter of Hades and twin sister to Nico Di Angelo, she's never seen what's above the Underworld or out of Olympus. But that changes when she sneaks out without her brother knowing and finds camp half-blood by mistake...

I know Five Below is the name of a store, I couldn't think of anything better