Seiren - Manhwa

One is a girl who has a strange illusion that she died at sea; Another is an athlete in the same year as her at school, who charms her with a look. Soon after, she falls into the water and is saved by her, and begins to want to start a friendship. Her best friend Suhasun suggests a plan to lend her a textbook. But Suhasun actually has an unhealthy crush on her, and wants to keep her by his side at any cost.