My System Is Three Thousand Years Early - Chapter 67 - 65: Practice Moderation

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

Have you ever thought a monster that has a job of a summoner and a tamer

what should it call itself Monster Summoner? Monster Tamer? but he itself was a monster too

Watch as our mc travels the world as an reincarnated human who turn into a monster

As a corporate drone, Ashu was transported to another world, hoping to live a life free from societal pressures.However, he quickly found that even marrying a village girl would cost him half of his wealth!Fortunately, just when things were looking grim, his childhood sweetheart—who had trained for many years—arrived to fulfill their childhood marriage pact. Not only that, Ashu activated the Crit Refund System, which allowed him to earn rewards by binding with beings rated over 90 points![Binding with the Witch Childhood Sweetheart, 10x Refund on Magic Potion, Host Gains: Forbidden Water (S)][Binding with the Forest Elf, 10x Refund, Host Gains: Infinite Stamina and Infinite Recovery][Binding with the Demon Huntress Nun, 20x Refund, Host Gains: Demon Slayer Holy Crossbow (SS)][Binding with the Imperial Princess, 100x Refund, Host Gains: Sigh of the Heavenly Father Spear (SSS)]Ashu: “The refund multiplier increases as our relationship grows? I’ll definitely have to dive deeper into this!”