Kakeru Diachi, a collector of rare juice cans, never imagined that his hobby would lead him to meet a fascinating new girl. When he attempts to “drink” her, he names her Melon, after her melon soda, and quickly learns that she is an Akikan: a beautiful girl who is also a special can created to fight other Akikans in a bizarre experiment testing whether steel or aluminum is the superior container. Kakeru’s involvement in this twisted research project complicates his life dramatically. Because Melon’s steel body requires carbon dioxide to breathe, he finds himself stuck with her, as she is heavily dependent on CO2.