Guardian Knight Elfina Falls

Koukotsu no Kishi Elfina
The noble knight Elfina tries to fight to the end to protect her princess, but the elven village has fallen at the hands of the humans.
Mordo, the leader of the humans, orders an exclusive onapet as a condition of surrender.
Elfina, who has had no experience with nocturnal sexual intercourse for more than two hundred years, falls into a state of unconsciousness as Mordo makes her do his bidding.