Bora (26 years old), Hyorin (25 years old), Soyou (24 years old) are older sisters of twin Dasom (23 years old) and Kihyun (23 years old).
Their parents had died, leaving them working hard to take care each other which made them tougher than any average women.
When suddenly their little brother is in love! Since Kihyun is the only male in the family, it makes his four sisters are over protective to him.
What do these sisters do to avoid bad things happen to their beloved brother? Will it unite them or break them apart as family?