Sing Swim the Series has a grand opening as the first BL series of a big TV station, TTV starring Most and Achi, the winners from the reality show Y-IDOL under producing of Phee, former top BL actor. Though there is good feedback from actors' fans, there is backlash from novel fans as well, so Most and Achi must please fans to stop negative news. During the shooting, they both meet Fern, the one and only female character in the series. She has a tough and cheerful personality and declares that she will act as a shipper to record Most-Achi sweet moments. In this way, the friendship between them starts during the shooting.

Most is very crazy about his relationship with Achi that he almost cannot keep the secret. In the shooting set, Most treats Achi so well that Fern feels bad and worried. And during the shooting of an NC scene, Most and Achi shock everyone with their very real acting that their emotions are still bubbling after the cut. Most and Achi cannot control themselves anymore, they make love in the set's bathroom. Fern sees that, and feels shocked and sad, so she reveals that she is dating Achi. Unfortunately, someone recorded this moment and sent it to the reporters.