Every day on his train ride to school, Makoto Itou notices the beautiful Kotonoha Katsura, but he is too shy to speak to her. Rumors circulate at his school about a charm: take a photo of your crush, set it as your phone wallpaper, and if no one sees it for three weeks, your love will come true. So Makoto takes a picture of the raven-haired beauty and continues to admire her from afar. However, when Sekai Saionji—the girl who sits next to him in class—sees the photo, she realizes he has a crush on Kotonoha and decides to help him with his romantic troubles. Eventually, Kotonoha and Makoto begin dating thanks to Sekai, and he wonders how he can ever repay her kindness. But to his shock, Sekai demands payment in a startling form: a kiss. School Days follows the complicated romantic entanglements of these three high school students, and the consequences that await them as a result of their poor decisions.