In Summer Night two high-school boys are competing for the love of the school's darling. The series is about a secret love that begins on the last night before the school's summer break. The high school's wallflower, Lune, and the school's golden girl, Star, start dating secretly. They decide to keep their relationship hidden because White, the school's wonder boy who introduces them to each other, is also in love with Star. This secret relationship on the summer night is the beginning of the chaotic story about friendship, love, and friction. How will this secret love end?