"I'll become your ideal lover. So please, give me one more chance." Says the figure who appears before Takenouchi Hiroto: his mentally unstable girlfriend, Koumoto Chise, whom he broke up with the day before―or rather, something taking her form. The girl, who calls herself Eiko, is a "Shapeshifter": a mysterious being that blends into society by devouring other creatures and mimicking them. Although she has taken Chise into herself, Eiko claims she hasn't fully absorbed her, instead keeping her contained within her body. Her demand is simple: "Even if it's only for a limited time, I want to live as your girlfriend. If you do that, I'll let Chise go." From that promise, a temporary relationship begins. But soon after they start dating, Hiroto realizes that he is more compatible with Eiko than he ever was with Chise. By spending time with this mysterious being, Hiroto's weary heart is healed, and he gradually remembers what it feels like to love someone. But that is precisely why, one day, he will have to face the fact that the girl before him is an "inhuman existence," living by laws different from those of people. And the bittersweet memories that made Hiroto who he is...
