Choi Ko-un, who loves his girlfriend so much he feels like he could die, and Han Song, who feels a bit shy about her overly affectionate boyfriend but still enjoys his love, are a happy couple. Their only worry is a small one: "What costume should we try tomorrow?" Today, they had another sweet and passionate time together. But suddenly, Han Song starts to feel bothered by thoughts of her ex-boyfriend and the opinions of people around her. She begins to wonder, "Will Ko-un ever change too...?" and starts feeling a little worried.