Monster Farm(1999)

モンスターファーム

Genki is a boy who loves playing the Monster Rancher games and one day he's somehow transported into the world of the video game where he meets the girl Holly and the monsters Mochi, Suezo, Golem, Tiger and Hare. Together, they are searching for a way to revive the Phoenix, which is the only monster capable of stopping the evil Moo.