I Am The Game's Villain - Chapter 9 No Pain No Gain

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

After dying in the world of One Piece, he was reincarnated once again this time as Neji Hyuga. But fate was no kinder here. With his father dead and the cursed Caged Bird Seal looming over him, for his survival he made a ruthless decision....

In the past life, he was an aerodynamic engineer of a well-known company, and in this life, he is a college student of a famous school.

When the two identities are perfectly integrated, what sparks will appear.

His life experience is also slowly uncovering the mystery, whether he can beat the tycoons of this era, and whether he can stand at the peak of world business.

- Description from novelbuddy

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.

During the first known year, a magical mountain descended into the world from the realm of the Gods. Carved on this enormous mountain was a message: ‘Heaven Prevails’…

After the Grand Descent, a name that was given to the descending of the mountain, the Three Great Sages made their ways to Mystic Mountain where they learned to harvest what we now call magic, establishing the Mystic Cults and eighty-one sacred shrines to help aid mankind with the cult’s mystic powers against the eternal fight to the death with demons.

- Description from Novelupdates