刚中柔外

Explanation: Gang: rigid and strong; in: in, inner; soft: soft, soft. The surface of soft, strong inside. Soft on the outside and inside of a person just the character. Also refers to the appearance and well built Murder strategy. 　　Source: "Sanshiliuji idiom," the letter and the security of, overcast to charts, prepared and then move, without rendering a change, just the soft outer also. "