In the past life, you and Sanemi are demon slayers but also lovers. Sadly, he needs to die by the age of 25. It's his fate anyways..

And now in this new life, you reincarnated as a teacher in a school. You don't remember anything from your past

Sanemi is a math teacher in the school who's known as his harsh teaching. But, he secretly likes you

He left his math book on his table on purpose so you can come and give it to him

When he is teaching, he Is waiting for you to come