
Near chapter 90 in the novel MC actually describes everything that happened in the dungeon in the detail. He actually remembers everything, each hunter that was in the dungeon, even the ones he didn’t know well, the ones who had a low rank and died at the very beginning. He remembers what they did, what their hobbies were, how they died, and the wills they left him. Most hunters left their will to him, because everybody knew that if anybody would survive, it would be him.
Spoiler
That dungeon will open again, if they won’t complete it and open the next dungeon inside of it, the world will end. That’s why MC has to describe everything that happened. It is also revealed that he pretty much has to take medicine to not go crazy. He remembers all the painful memories, but the happy ones with his dead comrades are too much for him to handle from what I've noticed. Also just wanted to remind everybody that the completion of the dungeon took 300 years.

It would be so hard for someone to open up about all of that. I knew he was in there for 300 years instead of 3 months. I know a new one will open up like the guy had that vision.
Which is weird, if the new one opening up has the same time limit then wouldn't it be insanely hard to beat it. Did the guy with the copy skill make it through the first dungeon, if he did then his is going to HAVE to be in the first dungeon to slow time.
I feel so bad for the MC. No one know exactly what happened to them in the great dungeon. The ML just wants to get to know him and get him to open up a bit, but I can't imagine how hard it will be to talk about it. Like, "oh, I do those things cause the people that started to die gave me a will so I am doing them so I can off myself after I'm done." Then explain how it all went down. How people were offing themselves in the dungeon and how they were actually in there for 300 years cause 2 guys made the time slow down to almost a stand still. Like, damn.