Aisa

Karen's stubborn sister and rival. Aisa's primary goal is to prove once and for all that she is the better Cupid of Love out of the two. Persistent to reach her goal, Aisa constantly challenges Karen in hopes of beating her, but ultimately never wins.

Although childish and rude, she deeply cares for Karen like a friend despite their fights and when she is serious Aisa is very perceptive and able to give useful advice which seem to exceed Karen's knowledge and direct way of thinking about relationships.