I Have a Monster House!

Before Xu Sheng moved to the city, he was cleaning up his old residence and found a letter. "A hundred years later, my old friend returns. If I am no longer here, please fulfill the promise on my behalf. ——Xu Sheng. " It's so weird that the writer of the letter has the same name as myself. When he looked away from the letter, a booklet appeared out of thin air where the envelope had been placed. I don't know whether it is official script or seal script, but there are three large dark red characters on the booklet. ——"The Collection of Demon Solving". At this point, Xu Sheng embarked on a path of no return with the demon.