"Monban Yattero" to Iware Juugo Nen, Tsuttatetteru Aida ni Ore no Maryoku ga 9999 "Saikyou" ni Sodattemashita - Vol. 3 Ch. 14

[MangaDex]

 

[ciera]

Thank you for the scanlation

 

[Nemo2342]

So did he dig his way into the dungeon next door? Or have we reach the back rooms?

 

[lesseffective]

I'll say that I had my expectations subverted that they didn't accidentally start in the Demi-Human Den.

 

[ThatNaiGuy]

I love all the ways he is as fully incompetent as you'd expect someone who was paid to stand in one spot for years and basically nothing else to be.

 

[Kortez]

How did they not hear/see a hole being blown in the wall behind them?

 

[Nemo2342]

I'll say that I had my expectations subverted that they didn't accidentally start in the Demi-Human Den.

I was expecting them to just somehow walk straight into the Demi-Human dungeon by mistake.

 

[FlameKingInferno]

WTF?! IT CAN TALK?!

 

[Kireato]

The surprise on that monster. XD

How did they not hear/see a hole being blown in the wall behind them?

It's definitely surprising, but I would say that:
They didn't see it because they're not looking at it. There's probably one entrance which they monitor so there's no need to patrol the rest room since no one would expect anyone to emerge from walls.
As for hearing it, I would have also expected some noise, but it's possible his spell doesn't exert any sort of force to destroy, but just straight up disintegrates the wall. And apparently it doesn't make much noise.
He's got pretty crazy spells.

 

[EmWeed]

I'll say that I had my expectations subverted that they didn't accidentally start in the Demi-Human Den.

They didn't start in the wrong Dungeon
But they still ended in the wrong Dungeon

 

[EmWeed]

I was expecting them to just somehow walk straight into the Demi-Human dungeon by mistake.

Well... Technically they just did