This request sounded troublesome, but fortunately, Bello, Ainsley's contracted beast, had a deep connection with the Underworld.
Even if the main world's Underworld was not located in the main world at all and was considered a separate higher-dimensional dimension, all reincarnation projects would be handed over to the Underworld.
The Underworld of the main world processed a lot of souls from various worlds that had the concept of the Underworld, including souls from low-level worlds and high-level worlds.
The 'main world' included many other high-level fantasy worlds, and so, the chance of souls from different worlds meeting each other in the Underworld was not low.
Of course, it was rumored that the Underworld created one zone after another for souls from each world to be processed so that the stronger souls would not make trouble such as bullying the weaker ones.