Chapter 10: Interstellar Migration (Please Subscribe)
The size of the inner world.
It was influenced by two aspects.
The first was the internal factor.
The second was the external factor.
The internal factor was the strength of the physical body, and the degree of understanding of the Space Rules, among other things.
Normally, the deeper the understanding of the Space Rules, the more core space models would be comprehended, and thus the larger the inner world would grow.
As for physical strength? It was difficult to significantly enhance physical strength in a short period of time.
However, slowly enhancing physical strength over a long period until reaching its limit was not difficult at all.
So,
for human Eighth Rank Evolvers, there were basically no problems in terms of the physical body.
As for external factors, they were some space-related rare treasures,
such as the incredibly precious 'World Fruit,' which could forcibly expand the size of the inner world when it was being established.