MTL - Harry Potter’s Book of Sin - Chapter 2542 Arrived at the Eastern Defense Line

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

Ling Chen was a peerless master hiding within the city hustle as a nobody-courier, until he stumbled into the world of the beautiful CEO, Nanrong Wanqing, the 'untouchable flower' of Donghai City, due to one of his work assignments. From then on, watch as his life is thrown into an exciting disarray!

Author Note: This story is only for those who like reading about overpowered protagonists, as our MC is going to be more than just overpowered.He is going to thrash anyone who comes in his way while enjoying his life.Also, it's a world travel novel; for those who have an interest in world travelling.................................................................The story is about a person who has lived through many lives, seen incredible things, and become one of the strongest if not the strongest beings around. Although he struggles to remember his past, he is determined to grow even stronger by utilizing his personal system as that would bring back his memories. He has one main mission - to enjoy life to the fullest - and he is absolutely committed to achieving it.Follow through the journey as he becomes the strongest (again?) and regains his memory while also enjoying his life along with his system and some other people.

To save a doomed fantasy world, I killed the main characters, then destroyed the game world, and fell into another timeline as the academy's top seat and rival to the protagonist.Now, I'm trying to save the world and steer it towards a better ending…But I'm the final boss.