Sixteen-year-old Kuroe Akaishi has spent most of her life keeping to herself, knowing that intense emotions cause parts of her body to mutate into monstrous appendages. Though resigned to a life of solitude, her monochromatic days find color when Arata Minami, a popular classmate, reaches out to her with kindness she never expected from anyone.

For Akaishi, however, Minami's growing presence in her life proves to be more troublesome than comforting. Despite cherishing his company, every interaction with him brings out stronger emotional responses, pushing the condition she has managed for years to its extremities, culminating in a complete transformation into a colossal kaiju. Now, Akaishi must navigate her growing affection while keeping her abhorrent condition hidden—before she becomes more than just national news.