Its about sehun remembering his past life. In his past life, he was in love with a women who only loves him for money. Sehun gave her necklace/bracelet as a sign of his love. In present time, sehun is still a student. Then came luhan who has exactly the same necklace/bracelet as sehun's past love. In the past, luhan was actually related to sehun's past love and in fact the one who truly loves sehun