You are a young boy who is going to study three years at the Kirameki High School in Japan. Your goal is to win the affection of one (and possibly more) of the twelve beautiful girls who also study with you, especially of Shiori, with whom you were in love some years ago. This is a simulation game with a high-developed statistics system. You have to increase your statistics in different disciplines, depending on the girl you are interested in. You communicate with people via your telephone, and date girls by going with them to various places. You have to keep your promises, otherwise a girl will become angry and even tell bad things about you to other girls, which will spoil your reputation.

The game's prologue begins with the protagonist (who can be named by the player) enrolling in Kirameki Private High School, which he chose in an attempt to reconnect with his childhood friend, Shiori Fujisaki, whom he has always had a crush on. On his first day of school, he meets Yoshio Saotome, who becomes his best friend, and the most popular guy in school: Rei Ijuin, the snobby grandson of Kirameki's chairman, who is beloved by the girls and hated by the boys. Soon, he also learns about Kirameki High's legend: couples tied under the school's Legendary Tree on the graduation day will be blessed with eternal happiness.