Tokumei Koukousei

The Myoga family has been fighting demons and evil spirits for generations. The newest members of the family are the twins Kaoru and Chiharu. Chiharu, the older sister, is skilled in spell casting while the brother, Kaoru, has yet to make it his own. Although they have sibling quarrels, they work well together but they need more than team work if they want to eliminate all the dangerous supernatural threats that are sprouting around the city.

(Source: MangaHelpers)