So I'm a spider, so what? (Light novels)

"A mystery man and a smartphone? Things are about to get interesting! I'm continuing to level up and kick some monster booty into the next stratum! But there's more to this world than I thought ... and it seems there are some big figures at play behind the scenes. Like this man, for example--he just popped up out of nowhere! And ... what's this? Holy crap, a cell phone! Maybe I'll finally be able to communicate with someone down here in this labyrinth...