The series tells the story of Kenji Tomosaka who moves to a seaside town when he was still very young. By knowing your new city walking, he saw the waves of the sea, which was lit up by the summer sun seemed like a vast sea of Lemonade (Lamune in Japanese).
At that time he meets a very nice girl, who befriends (Konoe Nanami). But not until the other day who discovers that his neighbor is his new friend, who not only lives next door if the windows of their rooms are so close together they can achieve their arms. So time goes by becoming bigger and bigger until their friendship in the summer of sophomore year this relationship begins to change.