At the beginning of a new year, Yonhee and Hokyung compete in the joint pep rally. Whereas Hokyung has a powerful team, Theia lacks the minimum number of members. Therefore, Jung-woo decides to choose two freshmen to perform with the squad. Through a physical test, Hae-yi and Sun-ho get chosen. To prepare for the rally, the fiercest training awaits the two.

The squad is busy getting ready for the joint pep rally. Jung-woo asks Hae-yi to overwork herself, and this leads the two on bad terms. Meanwhile, Sun-ho asks Hae-yi out once again, but she makes it clear this time that she is not interested. She hates Jung-woo for pushing her, but she feels something about him deep inside her heart.

Hae-yi becomes sad for a bit to know that Jung-woo has a girlfriend. However, she then learns from Sun-ja that the two captains have already broken up months ago. With that in mind, Hae-yi steps up to the stage to perform the Joint Pep Rally. But she does not know what kind of trouble awaits her on stage.

Although the joint pep rally is successful, Hae-yi could have been hurt badly if it wasn’t for Ha-jin and Sun-ho. Certain that this is not just an accident, Jung-woo digs in to find who is behind it. Theia goes on a field trip. The trip that should be filled with laughter and joy does not last that long. Someone is targeting Theia with bad intentions.

Yoo-min returns to the school saying that she has something left to do. Her sudden return is mysterious to everyone. Meanwhile, Theia is put in a tough spot as more than half of the freshmen quit after the release of the horrendous video. Hae-yi is also on the verge of quitting because of Min-jae’s proposal.

Jung-woo’s actions keep giving Hae-yi the wrong idea. But despite what he says, Jung-woo is also not sure what kind of emotions he has for Hae-yi. Meanwhile, Jae-yi gets into trouble at school. He beats up another kid and is about to get sued for it. However, Sun-ho promises to help him out for something in return.

Everyone has their own weakness, and so does Sun-ho. Although he is trying to find his own soft spot just to get Hae-yi’s attention, he actually realizes how hurt he is from it. Meanwhile, Jung-woo confronts Jae-min for what he did. He comes clean with the messages he sent but denies everything else. It turns out the sabotages are not done by a single person.

The day of the Yonhee Festival has come. The freshmen of Theia are extremely nervous as they will perform officially on stage. However, there are many things that Jung-woo must be concerned about. The freshmen performance might not take place due to a problem with the original singer, and the culprit who almost hurt Hae-yi might strike again.

After the successful performance of Theia, the squad heads to Cheers to celebrate. However, everyone gets overwhelmed by excitement and drinks until they black out. As they wake up, they find themselves in Busan. Hae-yi cannot remember anything except having a kiss with someone. Devastated, she tries to find out who it is.

The trip to Busan only makes it harder for Hae-yi to make her choice. Sun-ho kisses her and Jung-woo says he likes her. Although she tries to avoid the two guys ever since, the three groups up together for a dating assignment. After the date with each of them, she thinks deeply to find out who her heart truly desires.

Sun-ho is rejected by Hae-yi for the last time. Hae-yi and Jung-woo are now a couple but decide to keep it a secret from the others. Theia goes on a Summer Training camp. They go through passionate training and enjoy a pool party. However, an incident occurs that makes Sun-ja and Hae-yi drift away from each other.

Jin-il is the one who locked Hae-yi up and caused the fire. Thankfully, she makes it out in one piece. Jung-woo does not consider this an accident. He is certain that there is someone behind this. While Jung-woo and Cho-hee are trying to get to the bottom of this, Jin-il only makes the situation much worse.

The Hokyung University Cheering Squad visits Yonhee to prepare for the rivalry. The SBC Broadcast Station also wishes to film them and air them on TV, making the two squads more competitive. Meanwhile, Sun-ho and Jung-woo set things clear about Hae-yi. Sun-ho decides to give up on her, but will remain as her good friend.

Despite the happiness that Hae-yi is having with Jung-woo, she asks him to break up with her. It is because Chun-yang is diagnosed with breast cancer. In order to earn money for surgery, Hae-yi must work more jobs and cannot make time for Jung-woo. However, Jung-woo does not give up on her and neither does her friends on the cheering squad.

Jung-woo finds Hae-yi in time and saves her from life-threatening danger. Although he gets hospitalized for getting stabbed, he is just happy that Hae-yi is safe. After Jung-woo’s recovery, Theia focuses back on preparing for the Yonhee-Hokyung Rivalry. Despite all the troubles and hardships everyone goes through, they will always have each other to rely on.