The first criterion of royal elder sister is maturity. In other words, the personality is calm and calm, and the cognitive understanding of various things is multifaceted and complicated. The personality is strong, the mind is mature, and there is a noble temperament. The age can be roughly divided from 16-36 years old. This age range is basically divided according to probability, and there will be some special circumstances, which can be appropriately relaxed according to the situation.