With the summer in the sea, she draws the relationship between her younger brother and her older sister who is shaking out.故事发生在神圣时代的300年,主要讲述了初中二年级学生Yonaga Jicheng的故事。她每天在学校过着稳定的生活,上课,参加俱乐部活动,和很多朋友一起玩。