Sun and Nuea are dating, but Sun realizes that something is wrong with his 'physiology', so he quickly confides in his friend Third, who takes out a soap with magical effects and asks him to use it when taking a bath. Sun does so, but unexpectedly, Nuea suddenly joins him in the bath, and when he wakes up the next day, they actually exchange souls! They go to Third for help again, but a problem emerges.

Sun and Nuea use a 'special method' to undo the soul swap, but the troubles don't seem to be over. Sun's physical problems still bother him, making him feel inferior, and Nuea faints again and accidentally returns to Sun's body, and the souls are swapped again! Sun tries to switch back using a special method, but fails. At the same time, he also discovers Nuea's inner trauma and anxiety.

Sun and Nuea find out that if they continue to exchange bodies every 7 days, they won't be able to return to their original bodies after 49 days. In order to break the spell, the two of them and Third investigate the magic soap while realizing that their relationship has changed.

Sun and Nuea are gradually adapting to the life of soul-swapping, but the challenges continue to pile up. Just as the two of them reach their limit of their own respective challenges, they realize that the situation might help them understand each other better.

Sun and Nuea’s feelings deepen day by day, but the stress of not being in their own bodies builds. Nuea goes to a nightclub with friends to relax, but this causes tension in the relationship. However, after waking up, the two are returned to their own bodies.

As their souls continue to swap, Sun and Nuea decide to devote themselves to playing each other well, hiding their identities from being discovered while finding a way to crack the mystery. They go to work, attend meetings, and face colleagues and friends. Unexpectedly, the challenges of work become more and more difficult, and their pressure also increases.