Symmetry - A term that refers to shapes that are identical on both sides around an axis. Independent college student Ham Dain ambitiously plans to earn her living expenses through tutoring. However, as she struggles to find students more than she expected, she receives a call from one student. With a fluttering heart, she arrives at the officetel, where she is surprisingly greeted by a platinum-haired girl in a school uniform, someone she had encountered at school. The two, astonishingly identical as if looking in a mirror, are identical twins who entered the world just a few minutes apart. Asymmetry - A state where symmetry is not achieved and the shapes on both sides are unbalanced. The twins, who appear indistinguishable on the outside, exhibit completely different personalities. Unlike her younger sister, who is hot and lively like fire, the older sister has a cold and gloomy demeanor. Like a stark contrast of light and darkness, they each take an interest in Dain for different reasons. Moreover, as the twins get closer to Dain, the weight of their hearts begins to lose balance, starting to form a perfect asymmetry like a tilted seesaw.