One of the demon lords of seven deadly sins and truth of seven deadly sins and sinners

It has been 7 months and 10 days since James started his vigilante work. Tonight, James and Jack were resting in the cave, until the computer got activated. They checked it. It detected a large dark energy. They put on their clothes and went to investigate. When they reach to the place, there was a devil like person there. He used a black energy to destroy some old buildings. James and Jack approached him slowly. James jumped on him and Jack hit him with a kick. Then James said: Omae (I assume you are the demon lord of wrath, Leomaru, right?) The devil nodded. Jack said: (Do you know about this weird creature?) James said: Koitsu (I've read about him in legend books. Years ago, a strange creature come to earth. That creature had a power that was similar to the god, at first he was very kind-hearted, he forgive lots of people and helped anyone. He had some followers that had some power of him. Everything went peacefully. However, as the time pass, he become a corrupted person, wanting to destroy anything in the world. There was seven deadly sins, including: Pride, Envy, Wrath, Sloth, Greed, Gluttony and Lust. Seven of his members each commited one of this sins and become a demon lord. This devil like person is one of them.) Then Leomaru shot a black energy toward James and Jack. They dodged it. James said to Jack: Ore (Go and hide in a place, I know a way that might be able to defeat him. If it become necessary you come to help.) Jack said: (Okay, Dark nightmare-don.) Jack went to hide. James moved his hands in a strange way and his hands glowed to a white color. Leomaru shot another energy shot, James shot one toward it. The energy shots hit each other and exploded. Leomaru said: (Oh, it seems like you have some skill.) Then he shot two energy shots and James did the same too. They hit each other again and this time it exploded with more power than before and it give shockwaves, which pushed Leomaru and James, but they were able to keep their balance. Then James moved at a high speed and punched him, which put lot of damage. Then Leomaru said: (You fought very skillfully, I will see you again later.) Then he made smoke and left. James returned his hands to normal. Then James and Jack returned to the cave. Alfred brought them some food. They ate it and Jack explained what he saw and what happened, which shocked Alfred. Jack asked James: Anata (Dark nightmare-dono, what was that you use to fight that demon?) James said: (It was Sacred arts, he used Evil arts, Sacred and Evil arts are against each other, so I used this against him. You should learn this too, if you want to fight demons like him.) Jack said: (Yes, Dark nightmare-dono). Then James started teaching Jack how to use that.