Kyousogiga

The web anime Kyousogiga, created by studio Toei Animation and co-produced by toy maker Banpresto, was released for free online viewing in December 2011. Three kids are stuck in a strange city causing massive mayhem through the land. They are searching for an atypical rabbit in order to return home. Koto, the eldest of the three, seems to have some sort of connection to this weird place ruled by a monk, a demon, and a priest
Source : TVkon