Digimon Frontier: Ornismon Fukkatsu!!  

Digimon Frontier: Island of Lost Digimon, Digimon Frontier: Revival of the Ancient Digimon, デジモンフロンティア 古代デジモン（オニスモン）復活！！

Five kids discover an island with two distinct kinds of Digimons - Beasts and Humans. Upon seeing a friendship between two youthful Digimons of these categories, they conclude that action should be taken to resolve the conflict between them.