The Other Side of the Rainbow

Following his sister's demise, Ryousuke's folks split apart. Overwhelmed by helplessness, Ryousuke flees his abode and ends up on the other end of the rainbow in Nijigahara, a location devoid of the passing of time, where every inhabitant is a child. Nonetheless, with Ryousuke's arrival in the apparent utopia, will the fantasy realm crumble, and will Ryousuke ever return home?