This story is about a girl named Kang Seulgi who has an older sister named Kang Irene. Seulgi's crushing on Lee Jongin which is her senior but unfortunately Jongin doesn't seem to return her feelings and he seems to like Irene instead. Meanwhile Lee Taeyong is Jongin's younger brother who's also Seulgi's classmate and has been crushing on Seulgi for almost 2 years. 

It's a square love indeed.

Characters:

Kang Irene (left) - Kang Seulgi (right)

Lee Jongin (left) - Lee Taeyong (right)