Complex sentence: 'After facing Chihiro and Rea in his fencing room, he accepts Chihiro as Rea's protector but gives him a firm warning that there should be no "sexual intercourse before marriage".
Split into simpler sentences: 'After facing Chihiro and Rea in his fencing room, he accepts Chihiro as Rea's protector. With a firm warning to Chihiro that there should be no "sexual intercourse before marriage".