Because of a shipwreck, the second princess of the Deep Sea Palace, Haidemi, was forced to leave the Deep Sea Palace and go to the human world to escape the disaster.
She met Qiao Jingxi, who is known as a blue master, and the fragrance angel Yu Qinxuan; in order to prevent others from discovering her identity as a mermaid, and to experience campus life in the world, she pretended to be a student and entered the high school of Gao Sen International School, becoming a sophomore class A student.
However, this provoked a tit-for-tat confrontation from the barbarian princess Cai Sirou, who believed that she transferred to the school because of the popularity of Wang Qiao Jingxi. Therefore, she disliked her everywhere and vowed to knock her down.
Not to be outdone, Haidemi unfortunately got entangled with Qiao Jingxi during the fight back.
From being rejected by him at the beginning, to being secretly in love with him, he also dreamed of her secret identity as a mermaid; on the day of the school's Water Splashing Festival, she finally brought a big crisis to her...