MTL - Yu-Gi-Oh!: Underworld Boss, Cancerous Creator God - Chapter 6

Many people wish to become a character in a novel they like. Side characters are the best ones to reincarnate as. And Ceaser was the same. However, the problem is, the person he reborn as, was supposed to die at that time when Ceaser appears in the fantasy world. The childhood friend of the main heroine, who was supposed to be a stepping stone for the main lead so she can grow stronger. However, now that Ceaser was in that person’s body, naturally, he couldn’t let himself get killed just after rebirth. But what consequences will he bring by staying alive? And what awaits near the end of this story, about which even Ceaser is unaware?

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

Another entry in what you can call the Proto Harem Series: the books written before the Harem Series that take place in the same world.

It’s about a swordswoman whose student is captured, so she goes to rescue her.

“According to prophecy and scientific calculations, the entire world will see temperatures drop to minus forty degrees within three years, and even the earth's core will be frozen within three hundred years.”“What should we do?”“Gather all our strength, build a shelter together with unwavering unity. In the face of disaster, we must stand united, and everyone needs to do whatever they can to ensure a future for humanity!”“But what if someone refuses to work and just wants to eat and be lazy?”“Then let them die! Activate the alchemy golems and large robots, we do not support idlers!”Set in a scenario similar to Frostpunk, with fantasy elements and a steampunk background, viewer discretion is advised.