2boys, abs, ass, bara, blush, clothed_male_nude_male, couple, dark-skinned_male, dark_skin, demon_boy, demon_horns, demon_tail, demon_wings, formal, from_side, glowing, glowing_eyes, hand_grab, hand_on_another's_face, horns, kekkai_sensen, klaus_von_reinhertz, large_pectorals, leonardo_watch, long_sideburns, magic, male_focus, mature_male, monsterification, multiple_boys, muscular, muscular_male, mutton_chops, nore_(boosuke), nude, pants, pectorals, red_hair, seductive_smile, short_hair, sideburns, size_difference, smile, suspenders, tail, tail_raised, tusks, upper_body, wings, yaoi