Black Wolf (real name: Yushin Beck) is the leader of BiYong Palmu King's Guard.
Black Wolf has short, pale, gray-brown hair with messy bangs that mostly covers his eyes, which are the same color as his hair. He wears a gold earring in his left ear.
10 years ago, as the Crown Prince made his escape from the fire at the palace, YonRi Yoon ordered Black Wolf to find the prince and dispose of him. During the chase, Black Wolf threw a poisoned dagger and injured the prince. He ordered his guards to find the boy, but they end up failing to do so.
At JinHee Palace, as he heads for the meeting with his ministers, King JinWon asks Black Wolf if he found out anything about the girl he saw on the market street, and he informs him that she is the "Celestial Butterfly" of Yu HyangRu. Not much later, Black Wolf follows the king as he leaves the meeting, asking him where he is going. The king tells him not to follow him as he heads to Yu HyangRu.
After the Crimson Moon steals the real Covenant from Councillor Jagyum Yu's residence, Black Wolf assures the Councillor that he will deliver both the Covenant and the Crimson Moon to him. The Councillor calls him arrogant and reminds him that he failed to capture him 10 years ago. As Hwi Lee makes his escape from the palace with a smoke bomb after fighting White Pearl, Black Wolf injures him with one of his thrown poisoned daggers. Black Wolf then orders the guards to search for the injured man, who would be unable to go far.