S1·E10 Episode 10

Besides, NIN orders SO to carry out the social work harshly; thus, SO is unable to go for shopping. She then asks YUI to buy a hair accessory on her behalf. By accident, he meets YEK and KATE. Later, when YEK and KATE find that SO has put on the same hair accessory, they also misunderstand that YUI and SO are having an affair also. Nevertheless, YUI often stands for SO when CHI and NIN discuss the matter of SO. While the mystery is still prevailing, YUI and SO are infected and have lip sore together. All these coincident seem to prove their unusual relationship then.