Saetbyul (omega), who keeps his sex hidden from others, comes to realise that his classmate, Yul (alpha), is his soulmate. However, Yul believes that Saetbyul is a beta and therefore defines his feelings for Saetbyul as friendship. Soulmate or not, Saetbyul has no intention to pair-bond with an alpha; he ignores his own feelings for Yul. One day, Jaeyoung (omega) transfers into their class and is not hesitant to reveal his sex. Having known that Jaeyoung is an omega, Yul falls in love with him right away. As Saetbyul watches Yul, he begins to feel a sense of nagging...