Pumpkin Monster (南瓜の魔物) is a undead monster that is featured in Mass for the Dead.
While seemingly a plant type monster, the Pumpkin Monster is actually an undead. More specifically a type of astral monster acting on an intangible system and affecting the tangible world. However this creature was not natural, as it was spawned after pumpkin seeds were mutated by the Cracks making it a variant form of Contaminated Beast.
A eerily grinning pumpkin that resembles a living jack-o-lantern.
Pumpkin Monsters while not threatening by themselves, in groups are quite vicious. They are also quite intelligent, able to understand other beings and will act accordingly if threatened. Aura believes them to be a type of monster that lures prey by mimicking a pumpkin making it enticing to eat. Additionally the have very powerful regenerative abilities, able to reform themselves if shattered and even survive being digested inside a Redeem Slime.
The only way to destroy them is to hollow them up and light flame in inside, thus banishing the spirit and turning it into a jack-o-lantern. In addition in times of desperation especially when threatened by a superior foe, they will cannibalize each other, and unite to form a single Giant Pumpkin Monster. In Their hosts are not limited to just pumpkins, and they are able to take possession of other living beings by attaching the pumpkin to their prey's head, taking full control and increasing their host's physical abilities.
- In the game, Mare and Aura were commissioned by Momonga to cultivate a field of plants from the New World. They ended up with a crop of pumpkins, and brought them to Nazarick only to have an infestation on their hands upon realizing the plants' abilities.
- The Jack-O-Lantern is similar to the Pumpkin Monster though it is a seasonal event monster in YGGDRASIL.