Rilu Rilu Fairilu: Yousei no Door

Story

A collaborated multimedia character project between Sega Toys and Sanrio that will include a TV anime, merchandise, books, a game, and events. In the franchise's story, "Fairilu" are fairies of flowers, insects, mermaids, or other entities that are born from "Farilu Seeds." Each Fairilu is born with their own key, and they must search to find and open the door that fits only their key. Once the Fairilu pass through the doors, they mature. The doors are also related to the human world.

Synopsis via AniList (English).