One sunny day, a young boy named Jo-kang meets a curious young girl dressed in a bright yellow raincoat. She tells everyone in school that she is an alien and whomever she touches will be harmed. Everyone in that school becomes afraid of her, except Jo-kang. Jo-kang befriends the girl, Ari, and falls instantly in love with her. The quirky Ari loves telling Jo-kang stories, and he believes everything she says and is willing to do anything for her. After he and Ari huddle together beneath her yellow raincoat one rainy day, Jo-kang becomes sick with measles. Soon afterwards, she disappears.