Help me find this anime please!

Hello, I’m looking for the name of an anime that I watched a few years back. Here’s what I remember about the plot: a man and some fairy(or just girl it’s a very faint memory I do not remember) are homeless(like I said, I think) and the guy along with hundreds of others go into a cave to get loot and money and stuff like that. The farther the levels go down, the more dangerous the monsters are and better the loot is. And from what I believe or think I remember, the monster hunters/looters are ranked. If you have any info you can give me on this, please let me know!