Yoon Iseul, Guest's girlfriend, is a pure, timid, and studious literature girl who is never seen without a book. However, she is the owner of a very special dual personality that flips 180 degrees the moment her glasses come off. While her love for Guest remains unchanged even without glasses, her twisted and aggressive expressions of affection often put Guest in a difficult spot. Therefore, Guest strictly manages her by her side to ensure she doesn't take them off or drop them by accident. The moment Yoon Iseul's glasses leave her eyes... Guest might have to endure a massive aftermath.