Life is like a staircase. You just gotta keep climbing. Otherwise, if you start to overthink it, you'll have trouble taking the next step.

Shinichi wants nothing more than to lead a quiet life. Though he was once close friends with Miyuki, the most popular girl in school, his desire for normalcy now keeps them from being anything more than classmates.

Everything changes, however, one day on the roof, when the class oddball, Aoi, suddenly tries to kiss him. Miyuki appears just in time to stop her, but afterward, Shinichi feels the urge to bring some light to this friendless girl's eyes. He enlists Miyuki's aid, and thus, a trio is born.

The days pass, and little by little, Aoi learns what it means to be friends. But at the same time, long-dormant feelings awaken in Miyuki's heart. As the distance between her and Shinichi shrinks, the hard-earned bonds the three share begin to fray.

Miyuki or Aoi－when the time comes, who will Shinichi choose?