She was Primordial Yin, a legendary figure who once founded a devilish sect and shattered worlds. Now, after eons of slumber, Yin awakens in the most horrifying form imaginable: a flat-chested, chubby human toddler! Trapped in a mortal body and surrounded by a world she barely recognizes, how will this ancient being navigate a reality far tamer than her own, especially when she discovers she has lost her legendary boobs?

Two girls, Katsumi and Katsuko, identical in appearance but worlds apart in upbringing. One, a vibrant explosion of energy raised in Japan by her hero father, Dynamight. The other, a fiery spirit with a hidden artistic soul, growing up in France with her fashion designer mother. They've never known each other, until fate, or perhaps a mischievous summer camp, throws them together. What happens when two halves of a powerful whole collide, discovering a secret that reshapes their past and promises to ignite an unforgettable future?