Nanairo no Mukou

After his sister's death, Ryousuke's parents separate. Feeling utterly helpless, Ryousuke runs away from home and finds himself on the other side of the rainbow in Nijigahara, a place where time doesn't flow and everybody is a child. But, will Ryousuke's presence in this seeming utopia, bring the fantasy world to an end and will Ryousuke ever get back home?