Rental Magica from Solomon

Due to his father's disappearance, Itsuki Iba has to take over the family business: Astral Rental Magica, a magician dispatch service.  A Rental Magica company employs magicians and other supernatural beings in order to hire them out to those who need magical assistance.  He now has to be tough, commanding, and reliable, but there's one problem: he's a coward.  His personality also doesn't help him connect with his employees or face with those who threaten the family business--and some of the latter are supernaturally powerful and quite dangerous.