The Perfect Revenge of the Three Underworld Princesses

They once had a happy family, but why did they choose the path of revenge? Power? Money? No, because of revenge, they became best friends and family members, and participated in the unique training called a killer, just to one day avenge their families. . . . . . . However, when they were preparing for revenge, they met three young masters, and their appearance completely disrupted the situation. . . . . . ? This novel and its characters are purely fictitious. Any similarity is purely coincidental and should not be imitated.