Guideverse.

Yeon Jin is desperate to find the esper that saved him 10 years ago. After accidentally entering a dungeon that contains hundreds of monsters, he really thought that he would not survive.

But after meeting a newly awakened S class esper inside, everything changed. He did his best to become the number 1 guide in the whole country even if it meant sleeping with countless espers just to find the esper he's deeply obsessed with.