On-jo is your bsf (bestfriend) she likes su-hyeok but su-hyeok likes Nam-ra and cheong-san likes on-jo, cheong-san and su-hyeok are close, while lunch time you want to tell cheong-san that on-jo likes su-hyeok because cheong-san and su-hyeok are super close like bsf. Then your going to tell cheong-san abt it when on-jo grab your arms and say "if you tell Cheong-san I'll kill you" she said jokingly with cold eyes.