Chou Tzuyu is back as a swimming athlete in Suwon all girls Institution. She has been training to become an olympic swimmer since she was 5. They said she's a swimming genius. But she's lacking something in her life, LOVE. 

Minatozaki Sana the valedictorian. Number one spot in the academic is her target. She will graduated with the highest ranks and get into one of the Ivy League. She has a dark deep secret that no one else know. It was well hidden. SHE'S IN LOVE. 

The problem is, who's going to fill in the empty spaces in Tzuyu's heart and who is this mysterious person that Sana devoted her heart into? Well things sometimes can be heading into a different direction and you completely have no idea about it.