Four years ago, Dream Boy was an idol group that got embroiled in a scandal, and unfortunately the members went down the path of fallen idols. In the present... Jaeyoung, the member 'Happy' of Dream Boy, struggles with financial hardship and is working as a delivery rider. On receiving news that the leader of his now-defunct group, Sookyum, is passed out from over-drinking, he rushes to him.

There he meets Seungmin, who, unlike Jaeyoung, is the hottest rapper/producer at present and who shares the same stage name 'Happy'. Seungmin ends up saving Jaeyoung, who had passed out from an epileptic episode due to photosensitivity, and extends an offer for them to work together...

"You know who I am, don't you? Let us work. Twogether."