Might this be The Rise of the Unemployed Wise Man?
Karna was a boy that was given the title of "Wiseman" from heaven, is scouted by the hero party that had great expectations for his skills.
However, his skill "necromancer" was creepy and he was immediately exiled.
Karna, who got lost on the road without getting a reward, had accidentally invaded the Demon King territory and was targeted by the demons! He faced a demon with mighty power but defeats it with magic that overwhelmed it by far.
Meanwhile, Cecilia the demon, who saw the whole scene, offers Karna a large annual salary. And thus Karna decided to become an enemy of humanity as a magician with the Demon King army.
The main character is a young necromancer with blond hair, which looks white on the black & white pages. He gets kicked out of the hero's party though, because some of the other members of the party regard his skills as being "disgusting" (in reality though, it appears that at least part of the reason they don't like him is because he's so powerful that he makes them feel useless).
He subsequently encounters a female demon lord with long black hair, who is impressed by his powers, and hires him for a generous salary. There's also a young male demon he meets who is trying to win the favour of the female demon lord. He might be the character you mentioned who was bullied by his troops (a pair of demons do kind of make fun of him at one point).