MTL - Naruto’s Strongest Gentleman Training System - Chapter 13

The ordinary yet not so ordinary detective, Wen Wen, woke up in a mental hospital and discovered that his right hand was connected to a mysterious space called the 'Catastrophe Containment Facility,' from which he could acquire the powers of the monsters imprisoned within!By capturing a vampire, he gained a formidable physique;By capturing a ghost, he could turn invisible and pass through walls;By capturing a fox spirit, he could charm the opposite sex...In short, in order to obtain more powerful abilities, Wen Wen began to diligently capture monsters, thereby stepping into the strange world of superpowers and seeing the hidden truths behind the curtain...

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

Jun Wu Xiao = Almighty > author. The author accepts to design adventures for Him. So this work will never end, one adventure will lead to another (except the first one because of an error). If you want to read a book that will never end, then read this. Thank you!

The formless ancient world was infested with despicable demons. They hunted and feasted on mankind, keeping the human civilization constantly in a weak and suppressed state.