On a sunny day, a boy named Jo-kang meets Ari, a girl in a yellow raincoat, and they become friends. Jo-kang falls helplessly in love with the quirky but attractive Ari, but one day, she suddenly disappears. Ten years pass and Jo-kang, now a high school student, gets a call from Ari and meets her again in a temple. Although they have not seen each other for ten years, they have such a great time together. Then, Ari disappears again. Jo-kang is devastated. Why has she disappeared again? What will become of them?