Joujuu Senjin!! Mushibugyou

Story

In Feudal Japan, the people of Edo are under siege by giant insects that ravage the land. The people desperately beg the government to do something about it. Thus the Insect Magistrate Office is established, gathering strong warriors to defend against the onset of pests. Jinbee Tsukishima is a young man following the belief that a weak warrior isn't a warrior at all and strives to be a master swordsman just like his father. To atone for a horrific incident that occurred at his fault, Jinbee seeks to take his father's place as a member of the Insect Magistrate Office.

Synopsis via AniList (English).