Unlike back in the Great Source World, on the Akasha Continent, as long as Riezel used the Super Tier Magic Wish Upon a Star, he could easily cross planes and return from the Hidden World to the outside world.
After all, the Akasha Continent was unlike the Great Source World. For one, it did not have the power of the three Holy Swords sealing it off, and for another, the outside world and the Hidden World were not two sides of the same world like the Source and the Abyss.
The Source and the Abyss were truly separated by an entire dimension, making travel between them extremely difficult.
The Hidden World, on the other hand, was merely a Pocket Dimension. Though it was an independent space, it still ultimately depended on the Akasha Continent.
Thus, traveling between the Source and the Abyss often required paying an enormous price. Especially after the three Holy Swords sealed the Abyss, that price became so great that even the Abyss only dared launch one large-scale invasion, merely destroying "that empire."
With such a tremendous cost and such a powerful barrier in place, even consuming five entire levels' worth of Experience Points through Wish Upon a Star would not be enough to casually open a passage between the two.
But the Akasha Continent and the Hidden World were different.
It was merely a matter of teleporting from a Pocket Dimension to the outside continent. Even the Holy Temple could accomplish that through a large-scale Teleportation Magic Circle. Riezel only needed to spend a small amount of Experience Points to do it with ease.
Returning from the Hidden World to the outside world was not as difficult as reaching the Hidden World from outside. Otherwise, the price Riezel had to pay might have been even greater,