After the Marriage Cancellation, She Becomes a True Ancestor - Chapter 283

Yo, Hi! I’m Frank, I made a deal with a demon to pay me some money for receiving a guest for a few days every week.
I had no idea about what I have done.
On May 1st, Conan ‘the God of Death’ came to my house. I was forced to let him in and we get involved in a criminal case.
On May 8th, Bruce Wayne ‘Batman’ came to me. I was forced to follow him to fight crime.
On May 16th, Hannibal Lecter, The Silence of the Lambs, came to my home. I can only say that I really can’t stand my guests.

- Description from Novelupdates

"The boy has no powers," they claimed.

Instead of causing chaos with my knowledge of the original work, I assisted the protagonist.

I successfully completed the story and now planned to retire and live peacefully.

However, it seems the protagonist still needs my help.

An academy professor? That’s nothing much.

But why is the state of the academy so strange?”