A sazame bamboo flower, a harbinger of disaster blooms. A golden rainbow appears in the sky and a subterranean monster emerges. Ryumon is injured in this unprecedented situation. Kanata tries to cheer him up, but... What is Ryumon staring at? 

A mysterious giant plant appears and the pollen it spreads lures people into a world of dreams! But it looks just like R'lyeh, the plant Kengo Manaka grew to bring smiles to the people of Mars...?! A familiar face shows up as Kengo, Kanata, and crew try to take control of the situation, and the GUTS-Select joint extermination operations begins!