When Peak gains the least vote in the first week of Y-IDOL, he questions himself that talent is not enough for this show. Seeing Most and Achi gaining the most votes and creating moments make a naive boy want more airtime. But, the problem is Kla, his shipped partner. He always wants to expose Peak's girly manner, and when the mission of dancing week forces him to act as a sweet uke, Peak must carefully hide his weakness and feelings for Kla. He has to play the game along with hide feeling, can Peak do it?

Peak fakes his leg injury, so he doesn’t need to dance girly as the mission wants to do. The bright side is he gets the best scene and airtime, but the bad is Achi, his best rival acts like he knows the truth. How will Peak solve it? Moreover, Kla kisses Peak for what? Peak is confused and doesn’t know what to do next. Does he like Peak or just do it for airtime? And another drama, Peak has the privilege to choose a partner in singing week himself! Will Peak choose Kla as his heart desires or choose someone else to make him win in the next week?

Peak chooses Most, the best singer in Y-IDOL house, and randomly matches the rest hoping the rest will fail, but Kla and Earth can sing and dance perfectly together. Korn and Achi also seem to do a good job. So, Peak plans to play with Korn's head causing him to make a mistake on the stage and kiss Most to gain points from the committee. Peak’s plan has a great impact on everyone at Y-IDOl camp. Moreover, Peak’s parents pay a surprise visit at the camp. They have a fight with their son after seeing Peak kiss a boy on TV. Life crisis hits Peak so hard, so will he be open for Kla to heal his heart?

Y-IDOL boys receive the last mission as starring in a series for the last week. During shooting, Kla and Peak try to adjust to each other and clear the air between them. It makes Peak do a better job, but Achi notices that the show seems to have bias towards Peak or already places Peak as a winner. Achi put his bad opinions on the staff and got parole. Pond, the producer of the show, insists that there is no cheating at all, but after they arrive at the Y-IDOL camp, Pond calls for Peak and offers something that makes him hesitate, it was the offer that might change his life forever.

Eventually, the final round has arrived. Everyone has done a good job on the stage, but from the editing of the episode, it is obvious that the show wants Peak to be the winner and pairs him with someone else who is not Kla. Peak really feels bad for this injustice, and when the final question round arrives, what will Peak choose between prize or love? Who will be the winner of Y-IDOL? Will Peak’s parents come to watch his final round? And How will the relationship between Kla and Peak be? Does Peak have his own future in his hand now?

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.

Fern is sick, so Most and Achi go to her place to pay a visit and know that there are not only fans who appreciate their friendship but also fans who are anti-Fern. They have sent many hateful messages to Fern. Achi feels pity for her and soothes her, while Most has seen the caring attitude of Achi, and it impresses him. On the shooting set, Fern's motorcycle has crashed, so Achi has to drive her to her condominium. At this moment, both confess their feelings to each other and eventually have an intimate relationship.

The shooting becomes more serious. Most has to go through tough scenes with support from Achi. In the kissing scene, both Most and Achi feel some strange feelings inside. Most thinks about it and accept that he might really like Achi now. On a promoting day of the series, Achi's old rival puts him into trouble with his scandalous story in the past in the middle of the live streaming, but Most helps relieve the situation and end the live streaming well. Achi feels thankful for Most and starts to feel good with being treated well. And on that night, the relationship between Most and Achi goes far beyond just a shipped couple when Most drives Achi to his condominium on that night.

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.

The scandalous news of a shipped actor dating a girl becomes famous, and many people are interested in it. Many fans feel disappointed in Achi, while most are still in a state of shock after knowing the truth. Fern is fired by Phee while the shooting continues. Phee tells Achi to hold a press conference to refuse any excuse. But what will Most and Achi choose to handle this