As the leader of the notorious group Mitsukubi Condor, Marshmellow's fixation on aestheticism is unmatched. When a young woman named Cocoa seeks his assistance in locating her village's cherished harp, which possesses the miraculous ability to summon rainbows through its enchanting melodies, he begrudgingly agrees to help her retrieve it. This adventure unfolds in the one-shot story within Volume 3 of Mitsukubi Condor, which features two other stories in its collection: Ymir no Majin and Parasite B, contained within Volume 1 and Volume 2, respectively.