mmm, i'm not really into mermaids. .-.
phantom thieves are kinda like robin hood: they steal from rich people who deserve it, but they're not really about giving to the poor since they tend to be jewel and art thieves rather than straight-up money thieves, and precious jewels and art are really hard to distribute without arousing suspicion. they also tend to be uncatchable, and they don't kill, and they're supremely flashy like a stage magician. c=
ummm, also they tend to be chased by a sympathetic inspector character they have a friendly rivalry with!