My Demon-Slaying Teacher and Lovely Students

That day, I saved someone who was supposed to die, so I was entangled with her, and then forced to become her teacher. In the end, she also wanted to become a demon breaker like me, fight against demons, and protect the world. There is no other way, then I have to be her teacher for the rest of my life and protect my most lovely student for the rest of my life.