"Ji-ho and Seul go to bed after a successful first date. The next morning, they wake up only to find their genders swapped. Though they can't believe the reality, they worry and try to find a way to return to normal. At that moment, they reunite with Si-eun, Ji-ho's elementary school classmate. It turns out that in elementary school, Si-eun cursed them out of anger after being rejected by Ji-ho! The way to break the curse is for Ji-ho to realize true love. But what exactly is true love? Ji-ho's complicated romance to return to normal begins."