The young man leaves behind a key to another dimension where everybody's possible futures exist. Lum and Ataru join Shinobu to find the bunny boy, and happy futures for themselves.

Lum, Ataru, Mendou and Shinobu visit an inn which Ryuunosuke and her father have opened. But when it turns out to be on a haunted desert island, the stage is set for some serious silliness!