Torimori (from jap. 鳥 - tori, "bird"; コウモリ - kōmori, "bat"; 森 - mori, "forest") is a little bat-bird creature with their own individuality, goal, tastes and choices. First torimoris was created in Nyamrian Workshop by group of magicians. In many worlds, torimoris mainly use by countryfolks to protect the harvest, scaring off insects; and the nobles have torimoris as their companions, lovely pets, or as couriers/messengers.
They can exist almost in any world, but they still are something that you called closed species, because only professors from the Workshop know how to create torimori! Each such tori has the own soul and can be very different.
Since most torimoris have a mind and they are very sociable at all, one day some magicians decided to create the separate world for them. They called it Torimori Dimension, because the main population of this world is torimoris and the main biome is the forest. In Torimori Dimension they can do many things: from finding their own way to collecting useless trinkets and getting fun from anywhere!