The sequel to My BFF Key. Kim Kibum and Yang Kyungmi are good friends. BFFs to be exact. While friends are presumed to be tight-knit families, these two are rather different. With Key and Sooyun preparing to get married and Kyungmi and Onew contemplating to start a family, the two friends will begin to realize the strain of not only their friendship but their relationships as well.

Yang Kyungmi and Kim Kibum (or as he likes to be known as – Key) have been friends for a while. Not like childhood friends that have known each other since they were in diapers or friends from elementary or middle or high school. They’re just friends that met at events from other friends. But things start to change when Key breaks up with his girlfriend, Kyungmi's younger sister, Sooyun. In his attempt to try and win Sooyun back he discovers somethings. Was he in love with Sooyun?

Yong Junhyung has been dating Kim Hyuna for three months and twelve days. He likes Hyuna, he really does. But he can't help but forget all the important things about them - anniversaries, birthdays, dates.  He misses all the little details that mean a lot to her. And although he doesn't intend to be, Junhyung was so not boyfriend material.