The Princess Knight is a Classmate! summary:
After he and his entire class die on a field trip, Odamori accepts an offer from a mysterious man to be reincarnated. However his new job turns out to be that of a 'Slavemancer' with the power to dominate the minds of others and turn them into his toys, which he happily takes on. Soon however his evil actions lead to a Princess Knight (who turns out to be one of his previous, more popular classmates) being dispatched to apprehend him, but Odamori of course has something different planned for their reunion. (Source: Rapeman Scans)