Leather

Leather components are useful to craft the leather armor or clothing. They can also be used to craft certain weapons, such as The Guardian's Gauntlet or a whip. They are considered as common components. They can be recycled from monster fur or skin. If the player decides to do the pacifist route, leather would be harder to find excluding purchasing, because leather comes from dead monsters.

Monsters do not kill each other for fur or skin. To get leather, they wait until someone dies. Upon the person's death, they would "scrap" the corpse, re-using their bones, their skin, etc. This method in the underground is called Corpse-Recycling.