There was a system in the world that determined people's soulmates from the moment they were born. Each person had their own pair. You could find a pair by a mark on their ribs or wrist. When a soulmate was nearby, the other half would feel a very strong burning sensation from the mark. The only way to stop this burning sensation was to kiss the mark. When people turned 20, they would begin to smell. These smells are always associated with soulmates. Yeonjun didn't believe it, he had been alone since childhood and was used to being alone. His classmates at university thought he was weird and didn't talk to him, so there was no point in hoping for a soulmate.

Yeonjun is standing on the balcony sipping soda. Their university was throwing a party at someone's apartment and Yeonjun came here so that his thoughts wouldn't bother him too much when he was alone. Soobin, a popular guy at university, comes and stands next to Yeonjun. Soobin was known for his kindness.

"Why are you here alone? Don't you like noise?"

Soobin asks looking at Yeonjun.