One day Saiki and his friends heard on the news that there was a ship reck near them so they got their scuba stuff on and got in the water and as Saiki, Nendo, Kaido, Aren,Hairo, and Teruhashi where swimming they found the ship but they could also see movement but it was going too fast then.... They saw it... A GODDAMN SIREN... But it's actually... Pretty... It's either a Siren or a Mermaid