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Sludge Jellyfish (ヘドロクラゲ, Hedoro Kurage; Viz: Hedro-Jellyfish) was a Tiger-level Mysterious Being and a member of the Monster Association. It was one of the Mysterious Beings who assaulted S-City alongside Elder Centipede. He was killed by Evil Natural Water.[2]


Sludge Jellyfish was a walking blob of sludge.

After his first encounter with Garou, Sludge Jellyfish adopted a more humanoid appearance and changed his form so that he had two legs and several tentacles.


Sludge Jellyfish was one of the more friendly monsters to appear, alongside Phoenix Man. It even tried to invite Garou to join the Monster Association despite the latter attacking it. However, Sludge Jellyfish did not forget the incident and got revenge by holding Tareo as a hostage to mess with Garou: his vengeful side showed itself again when he prepared to kill Child Emperor and openly admitted he was the type to hold grudges. Like most monsters, he was rather fearful of powerful heroes such as King and Tatsumaki, and was scared at the mere mention of their name. However, he was very confident in the power of the Executive Members of the Monster Association, stating that they would defeat all the heroes, and it was as if they were created by "God" himself.

Like Phoenix Man, Sludge Jellyfish was one of the few rational monsters, who wasn't prompt to kill humans or attack them on sight. He engaged in a conversation with Tareo and Waganma.


Human Monster SagaEdit

Monster Raid ArcEdit

Sludge Jellyfish is first seen in S-City accompanied by Phoenix Man and Rhino Wrestler. The three monsters corner Mohican and Pineapple, who are carrying Narinki and his son Waganma.[3] Sludge Jellyfish is first seen watching the battle between Garou and Metal Bat alongside Phoenix Man.[4] After the fight is finished, it tries to kidnap Zenko, only to be intercepted by Garou and brutally smashed by him for watching over the hero hunter.[5]
Sludge Capture

Sludge Jellyfish captures Tareo.

However, thanks to its regenerative abilities, Sludge Jellyfish survives Garou's attack. While angry, Sludge Jellyfish still tries to invite Garou to join the Monster Association. Unfortunately, the invitation is rudely turned down. Sludge Jellyfish then leaves alongside Phoenix Man.[6]

Monster Association ArcEdit

He later surfaces again during Garou's fight with Bug God and Royal Ripper in which he captures Tareo to mess with Garou for attacking it earlier. His action causes Garou to be distracted long enough for Bug God and Royal Ripper to deal multiple fatal blows to him, making Garou seemingly appear dead. Afterward, he, Royal Ripper and Bug God kidnap Tareo back to the Monster Association HQ as a hostage.[7]

Sludge Jellyfish goes to the cell where Tareo and Waganma are being held and tells them there is no hope for either of them to be saved. Waganma disagrees, and says the Hero Association has plenty of heroes, and goes off to list the names of several heroes, such as Metal Bat and King. At the mention of King's name, Sludge Jellyfish becomes frightened, but confidently states the whole purpose of the Monster Association is to eliminate such heroes, and goes on to mention the executive members of the Monster Association, speaking in awe of their strength and remarking they must have been created by God. He states that there is no way humanity can win, and even King will fall.

Sludge jellyfish death

Child Emperor burns Sludge Jellyfish.

When Child Emperor breaks into Waganma's jail cell, Sludge Jellyfish attacks the hero. Filled with confidence in his liquid body, the monster arrogantly attacks the hero only to be blown apart by the oils Child Emperor injects into his body.[8] He is later revealed to be alive when he appears in the middle of Child Emperor and Evil Natural Water's fight, but his oils are absorbed by Evil Natural Water, leaving his body as a shriveled husk and permanently killing it.[9]

Abilities and PowersEdit

Not much is known about Sludge Jellyfish's strength, except that it was one of the few known monsters with regenerative abilities.

Physical AbilitiesEdit

Liquid Body: Sludge Jellyfish's body was made up of liquids and therefore had no discernible weak points. Physical attacks did not have much effect on the monster. His body seemed to naturally absorb all liquids including flammable liquids.[10]

Enhanced Durability: Sludge Jellyfish was able to survive being burnt to a crisp by Child Emperor's liquid fuel and prepared to fight Child Emperor again.[11]

Regeneration: Sludge Jellyfish possessed a form of regeneration stemming from its liquid body. It was able to regenerate back from being turned into essentially a pile of goo after being smashed into the ground by Garou. Its regeneration helped it survive being burned by Child Emperor, although when drained of its liquid oils, Sludge Jellyfish's regeneration is halted and he cannot recover from wounds.

Poison Immunity: Sludge Jellyfish was immune to poison, as shown when he was completely unaffected by Child Emperor's poisonous gas, which killed several other monsters.[12]

Fighting StyleEdit

Hand-to-Hand Combatant: Sludge Jellyfish's fighting style was basic and involved using his body to constrict his opponents or slam into them.[13]

  • Sludge Press (ヘドロプレス, Hedoropuresu): Sludge Jellyfish drops onto his opponent.[14]

Major BattlesEdit

Participants Chapter(s) Episode(s) Result
Sludge Jellyfish vs. Child Emperor 97 None Loss


  1. One-Punch Man Manga; Chapter 97, page 22
  2. One-Punch Man Manga; Chapter 122
  3. One-Punch Man Manga; Chapter 58, page 11-13
  4. One-Punch Man Manga; Chapter 58, page 48
  5. One-Punch Man Manga; Chapter 59, page 4-6
  6. One-Punch Man Manga; Chapter 59, page 7-9
  7. One-Punch Man Manga; Chapter 88
  8. One-Punch Man Manga; Chapter 97, page 22-25
  9. One-Punch Man Manga; Chapter 122
  10. One-Punch Man Manga; Chapter 122, page 3
  11. One-Punch Man Manga; Chapter 122, page 3
  12. One-Punch Man Manga; Chapter 97, page 23
  13. One-Punch Man Manga; Chapter 97, page 22
  14. One-Punch Man Manga; Chapter 97, page 22


Monster Association
Leaders OrochiPsykos
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Dragon Gale Wind Hellfire Flame Phoenix Man 
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Tiger Destrochloridium Electric Catfish Man Mad Doctor Fish Maiko Plasma Marshall Gorilla Sludge Jellyfish 
Unknown Eyesight Gyoffrey Goddess Glasses Venus Mantrap Junior Centipede Haragiri Rosie Choze Benpatsu Hamukichi Volten Evil Eye Gale Hellfire Evil Eggs Sword Devil Executioner 
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Native Tribes Forest Tribe (Forest King ) • Seafolk (Deep Sea King Lord Great White Messenger of the Seafolk ) • Skyfolk (Sky King Eagle Hawk Falcon Kite ) • Subterranean People (Subterranean King ) • Terror Lizard Clan ( Ancient King )
Dark Matter Thieves Boros Geryuganshoop Melzargard Groribas Dark Matter Gunner 
The Organization G4 G5 
House of Evolution Carnage Kabuto Beast King Armored GorillaKamakyuri Ground Dragon Frog Man Slugerous Mosquito Girl 
Anime-Only Mysterious Beings Super Custom YO649Z Mk. II Fish of Darkness *Pluton Men's Esthetician Man *Dirt Earthworm Japanese Giant Salamander Lord of Mountains TV Junkyard Monster Urn Eel Crazy Brown Bear 
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