Rito's always been a plant-lover, and when the family's giant sentient plant Celine comes down with a fatal illness, he's willing to do whatever it takes to find the cure. It'll be a long trip to find it...a trip all the way to outer space! Rito and all three of the Deviluke sisters are off to the planet Mistletoe, where all manner of strange and dangerous plants make their home. It'll take everything they have to come out on top!