Big bang (and maybe the rest of YG?) are back in art school. They are in seperate grades according to age and its generally pretty cute. The parings are gtop and baeri...sorry Daesung you can find a nice girl. 

general summary:

Jiyong and Seung-hyun(TOP) are in the same vocal ensemble class and have to do a rap together. They're the best in the class. Jiyong is a bit intimidated by is hyung, who is very serious in class (at least of what he's seen) and isn't too excited to work with him. Their friendship and eventual feelings for each other grow from having to spend time togeher working on this project.

Youngbae has to tutor/teach Seung-hyun(VI) how to play piano for one of his classes cause he missed some class cause he was sick. This is right after his dance class. They start to bond over spending time learning/teaching piano and a shared interest in dance. Seung-hyun is more interested or more active in his feelings than Youngbae who treats him like a little brother. 

Daesung is the oblivious bystander ho tries to make everyone happy.