Literally had forgotten this existed, had stopped around chapter 19 and today readed the whole thing.
4 stars - Bad imo
Imho the plot had lots of things being done right, but when the autor started to introduce new elements to the story it all became a mess:
-the "god-like" japanese girl that the god was teasing (by leading mc to her first, before he sended him to Mia), I guess we can think that she was like a toy of the god who couldn't go to him or some shit like that, thus why he sended the other girl(secretary) to play with her (maybe teasing her, idk)(wouldn't make much sense other wise)
-then we get to see his chf who was probably stronger than him by the time they met outside the wizard's laboratory (which doesn't make much sense as even if time flows slower inside the dungeon, the monsters are stronger there, when the god or the other girl wanted mc to become stronger they wanted him getting exp inside the dungeon and not outside)
-Revenge was bad, the bully and the slave owner did a much better job at doing her life miserable than mc who I think wouldn't even try to fight chf if Mia hadn't been killed in front of his eyes. At least the chf revenge on the bully was "good".
-CHF was a rotten apple who got treated as a whore and later tortured and become a "spoiled rotten apple". I don't know what was her personality at all, was she rotten to the core because of her's "trying to survive" ideology or was she broken after the betrayal and the torture? IDK, she wanted to kill mc as a way to forgive herself for betraying him but as she is dying she says she is sorry for everything she done to him (was that a momment of clarity of her old self from before being isekaied?). Her personality was a mess even for woman standards.
-Time flowing different in the dungeon. I think it was a neat idea showing the little kid mc saved and later having the old guy be someone who entered that world/dungeon after mc (but somehow would deliver his messages before mc could enter/face the challenge of the room). There is little explanation to why this was happening, and it wouldn't be hard to explain it, for exemple "god or that other girl were manipulating the time from mc's journey in the dungeon to make sure chf couldn't track him" or some other thing like that but that doesn't explains why the fragment of the nether king was in the first room where mc saw the first message from the old guy, why the nether god was in the castle of the old man, and why making mc fuse with the king was necessary for the overpowered girl to defeat the monster (the monster and the moment she defeated the monster was in the past = before the old guy started to explore the dungeon; but the nether king and mc journey were in the future)(I get that mc also needed the power to defeat chf BUT either the nether king joined the dungeon after they defeated it and the japanese overpowered girl lied to mc about needing to defeat it or it was just a plot hole)
I think the concept was good but it was badly written, if it was a novel adaptation then I hope the novel at least has some answers or shine a better light into some of those issues.