Sasen Deshitara Yorokonde!: Oukyuu Majutsushi no Dai Ni no Jinsei wa Nonbiri, Mofumofu, Tokidoki Kinoko?

Doma, the chief magician of the royal palace, was demoted after headbutting his unreasonable superior. He's fallen off the elite track and is practically dead as a royal magician—but for Doma, who craves a slow life in the frontier, the demotion is the ultimate reward! Excited to finally be able to live a carefree life of magic research, Doma heads off to his new location. However, as the strongest magician, he can't expect to live such a peaceful life, and he gets caught up in trouble, fighting a gang of thieves and having to investigate a haunted house. Furthermore, a motley crew of unique companions gathers around him, including a naturally strong and beautiful female swordswoman and a spoiled mushroom fairy! His ideal is a slow life, but his second life seems destined to be chaotic...!? The long-awaited comic adaptation of the winner of the 2nd Next Generation Fantasy Cup!!

(Source: AlphaPolis, translated)