it is not DN angel, this manga seems published around 2006++

the story is about a kingdom, the king ruled with iron fist. He was'nt that tyrant but he turned into one when his wife, the queen got sick. The king somehow have a black wing, it is a weird trait that some people born with(a wing, horn, claw or such). People called it as demon or monster and don't see them as human.

The king have black wing, but he was very strong, his strengh was beyond human, nobody dare to oppose him, he have a son who shared this trait, a black wing. The king loved his wife dearly, and he waged war on many country to find a medicene that can cured his wife ilness. Many country falls in his hands and he always targeted the country who have the most advanced healing medicene. Somehow he managed to get some medicine that can slow his wife ilness, but it is not enough and he still waged war to other country to find a true cure for his wife ilness.

In the end, after some years, the king suddenly disappered along with his wife. The new king was his son, he was around 15-16 years old. He was quite scary, and have this evil personality , and he also have a monstrous strengh, nobody dare to oppose his ascension as new king.

The new king, then was quite mad because his father leaving the throne without telling him anything and bringing his sick mother with him. He then want to go on journey to find his parents. He also think he need a companion to guide him, so he hired a femine looking boy. The boy was a prince from another country that has been conquered by the previous king, and his country was in ruin because they can't provide the medicine.

I think in the middle of the story , the prince was trying to kill the new king but failed because he was too strong. The new king was amused and made a deal with him, if he found out where his parents are, he will give the throne because he dislike ruling over people who look him as monster , his empire to the prince. the prince then surpised but agreed on it but still confused why he do it.

along with journey they meet many people , and a girl who works as black smith, she was so strong and people call her monster because she have demon horn and have a friend who was a nun in the church. I remember the nun try to kill her because she was afraid of her despite befriending her, in the end she apologized and it got wrapped.

The ending is, that the new king found out the truth about his parents, and the prince become the king that replaced him. I think our mc just left on journey.