Fairilu are fairies that sprout from special seeds, and each one comes into being holding a key of its own. That key fits exactly one door, and every Fairilu has to seek out and unlock the door meant for it alone. Some are fairies of flowers, others of insects, mermaids or other things. Stepping through their door is how a Fairilu grows up. These doors are also tied in some way to the human world. Rilu Rilu Fairilu: Yousei no Door is a gentle fantasy slice-of-life TV series that runs for 59 episodes, and it forms part of a multimedia character project created jointly by Sega Toys and Sanrio.