Jay, an international student from Thailand, comes to Korea to see his friend Seong Hun. The two enrolled in the same college class called "Health and Happiness" and need to submit a physical body assessment for their final project. While Seong Hun already works out regularly, Jay isn't in the greatest shape and struggles in the gym. Enter Jin Uk, a personal trainer who takes a special interest in Jay, much to Seong Hun’s displeasure. However, there's something strange about Jin Uk. Despite his kindness toward Jay, suspicions begin to rise that Jin Uk may be involved in a murder and missing person incident. Is there a happy ending in store for Jay and Seong Hun, or will Jay's budding relationship with Jin Uk cost him an unspeakable price?

Gap is the frontman of an unknown band called Evening Sunday and Namwa is a devoted member of the fandom of a ghost ship. After a messy first meeting, the two are thrown into a group project together at university. Through her connections, Gap's band gets the opportunity to rehearse in a high-class studio where they learn that Namwa is the younger sister of a world-famous music producer. Gap thinks he can get Namwa to help Evening Sunday grow.

Ai studied abroad until, but after being expelled for quarrelling, his father forces him to return to Thailand where he attends classes at the university where he teaches. There, Ai meets Chen Nhai, his new Harley Davidson-riding classmate who has an obsession with a yellow duck keychain. Ai falls in love at first sight and a whirlwind romance ensues.