Gusmanak is a member of the Den. By giving this NPC a Can of Worms, as well as the respective items for the other members of the Den, a Rukiryaxe will be given to players or an End Times Axe on Halloween 2016. In the Den, he is seen to the left of the table.
Gusmanak, as with all the other Den members, is mentioned in one of the Rukiryaxe Posters, saying "EATS DIRT EATS WORMS EATS DRYWALL LICKS STATUES STEALS GARBAGE", giving the player a hint of the recipe for the Rukiryaxe. He is based on the real ROBLOX user with the same name.
In order to find the character in the Den, the player must travel to the Taiga Biome, (making sure to bring Dynamite in order to pass the boulders blocking the entrance) and locate the Hatch which grants the player entrance to the Den. Because the Hatch is covered with snow, the player must find the red eagle. The Den is located somewhat directly under that.