Lilith

As far as anyone can tell, Jaehee is a shy, hard-working high school teacher. Once she’s behind closed doors and drawn curtains, Jaehee enjoys spending her time kneeling at the end of a whip. And no one enjoys holding the handle more than her childhood friend, Huilin. But, when Sulhwa starts her position as a student-teacher at the school, secrets and feelings long buried start to surface. Now, Jaehee’s about to learn just how much pleasure she can pull from pain.
The continuation is Lilith 2