one who is of a mixed yōkai (妖怪; supernatural being/demon) and ningen (人間; human/mortal) heritage.

both sides / both parties

characteristic, peculiarity, property

yokai: supernatural being, monster, apparition, goblin

(dated) creepy, spooky, ghastly, perilous

and a half

to hold, to carry something / to have, to possess / to hold up, to maintain

holding, possession / wear, durability

continuative of 持つ

he / distal demonstrative, something far off removed from both speaker and listener: that / boyfriend