I want to find a manga (maybe black and white) that I read last year with this storyline:

A manga that tells the story of a hero who was fired/kick out from his party due to the cruel way he went about his work. He then met a former demon leader  who was kicked out from the devil lord castle and got bullied by his troops.

The main character is a man who has white hair. And the heroine, I don't remember too much, maybe has long black hair with glasses.