Trinity Seven, Vol. 4: The Seven Magicians — Kenji Saito

One of Trinity Seven's own members, the fiendish Liese, attacks Arata with a "passionate kiss" that purloins all of his magical powers! With the Demon Lord Candidate's magic in her possession, Liese's powers are unmatched. But the key to defeating Liese must lie with the Demon Lord Candidate himself! How will Arata bear up under cruel and unusual training?!
It's Volume 4 of this romantic comedy and sometimes-serious wizard school story!