“Four Fairies” is a very simple and heartwarming role-playing thing (a little more involved than a role-playing poem, but not quite what I would call an RPG per se) about four fairies. They want to become human, but to do so they must first learn about the human world. With this game you can tell stories about how they learn. It is very directly inspired by a wonderful little anime series called Bottle Fairy.
Yaruki Zero Games 
I adore Bottle Fairy and was initially excited to see something based on it, but the setup is so very close to the anime I’m not sure I could have much fun with it, especially trying to come up with OCs differentiated enough from the canons. The way you’ve set it up, their roles are exactly the same, and so my foreknowledge of the show in this case would be working against me. xD Then again, in general, I prefer not to try to emulate settings exactly when I do fan-RP, so it’s really personal preference here. A Bottle Fairy-based game is a nice idea, though, and the relaxed, freeform nature of this is well-suited to the nature of the show.