Guest and Kang Harin have been childhood friends since they were little and ended up attending the same university.

At a drinking party, a joke about whether the two were dating turned into a 'yes,' and it snowballed until they ended up pretending to be a couple. Although they've spent their whole lives thinking of each other as just friends, they're starting to feel a strange sensation.

The two are forced to take a couple proof photo due to the persistent requests of their friends who want them to send one.