In order to uncover the "end of the sky," as spoken of in ancient mythology, Kal-el Albus is sent to Isla, an island in the sky. There he attends Cadoques High's Aerial Division, where he enjoys a carefree life with his schoolmates. That is...until a surprise attack by the air tribe drags Isla into a bloody war.
While searching for a run-away cat the twins Riko and Rimu Mikogami find a strange device that transforms them into "Kirumin." It also enables them to turn into real animals. Their older sister Nagisa soon joins them. Now the three have cute, funny and sometimes dangerous adventures.
