[Dazai, indeed, would touch the hole. The walls looked thick, to be sure, and that wasn't the kind of crack that ran deep.]

This is obviously conjecture, and I can be entirely wrong.

It's possible that this Master might soon face difficulties in keeping this up, or that the walls closer in proximity to him are better formed. Alternatively, details like the stones used are an afterthought, and not necessary to the fundamental formation of the labyrinth.

However, if mana is an issue, we should already have encountered the Servant at this point. There's no merit in dragging on this engagement in that scenario.

[He glances down at their lifeline connected to the exit - how thick or thin are the layers of thread left on the spool?]