カズト

Race: Human
Role: Adventurer

An adventurer who especially loves dungeons. He spends his free time researching old dungeons. When his adventurer party breaks up and he is broke, Fuu appears before him with an job offer:

Use his expertise to design a dungeon that will attract adventurers from all over. Doing so will help gather funds necessary to excavate the 5 seals that are restricting the Demon Queen Karin.

While a bit hesitant, Kazuto accepts, eager at the possibility of designing his own dungeon, though with the understanding that the dungeon will not seek to kill any adventurers, only take their money.

In Karin's events, it is revealed that Kazuto is descended from the sibling of the "hero" that sealed Karin away. That sibling sided with Karin.