Oh Sehun. The obedient Mr-Goody-Two-Shoes. Cold mannered yet warm hearted. Poker faced, but not hypocrite. Superior IQ, basketball team MVP and supreme dancer. He currently concentrated and focused in his upcoming position as CEO of Oh Enterprise. Not for wealth, but for his own ego. He tempted of success and reach that position gonna prove himself in his father eyes. Deep inside, he is calm, wise, thoughtful, gentle and mature man but smartly hid by his empty eyes and half hearted smile. Yet, he is lonesome. Wary man with childlike reverie. He fell in love once, the one and only love he want and the love that he want to throw away. Love that susceptible to their twenty years of friendship.

Krystal Jung. Free spirited rebellious girl. Born with effortless beauty and natural intelligence. Gifted with determine and hard work. A girl that hard to handle and even harder to understand. Freshmen student of Seoul University. Previously, Nation golden medals holder for female gymnast, archer Goddess, basketball team playmaker, dance club ace, leading female model and angel-voiced singer. She had no interest to the company. Often misunderstood. She is childish, stubborn, reckless, sloppy and sharp tongued, yet she kind, fragile and vulnerable hearted. The combination of angel heart and crooked devilish teenager. Her heart belong to someone, someone closer than anyone thought. She refused to admit, but yes, soon or later she has to accept that her heart rooted for him. 

Typical love story of best friends entrenched as one. Simultaneously grew feelings, unusual feelings that jeopardize their friendship existence.