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For the Virus, see Gastrea Virus.

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Gastrea (ガストレア Gasutorea) are deadly parasites; enemy to all mankind.


It is unclear how the Gastrea Virus first began, but it has been recorded in history that it was created around the year 2021. An accidental government uploading of a clip uncovered by Doctor Sumire Muroto revealed that the first Gastrea was made in a lab utilizing a woman's body. The file was named the "Ardi File" after the supposed oldest fossil of a 4.1 million-year-old ape-man, named Ardipithecus ramidus, or Ardi for short.[1]

Though it is not confirmed, Rentaro theorizes that the reason the first subject was a woman may have to do with why all Cursed Children are girls, as well. The Mitochondrial Eve, named after Eve from The Bible, was also theorized to be the first human, as revealed from studying mitochondria ten years ago in 2021. However, the mitochondria were only passed down through the female family line, subsequently leading Rentaro to reach his conclusion.[1]

The clip named the Gastrea Virus as the "Devil's Virus". The origin of the name "Gastrea" is unknown, which confused Rentaro, but Sumire suspects that it is simply due to the fact that names change when they are subjected to the general public.[1]

Essentially, the virus enters the human body through bodily fluids and turns the human into what is known as a Gastrea. After the breakout, Gastrea quickly took mankind's spot at the top of the food chain, almost destroying humanity and taking over most of their land during the Great Gastrea War.[2] The human population was reduced from almost 8 billion to around 10% of what it was before, with the rest all having turned into Gastrea or perishing.


Gastrea are deadly parasites that have risen to the top of the food chain in the past 10 years, defeating the humans in the year 2021. Although they are clouded in mysteries, most Gastrea are humans infected with the Gastrea Virus, which gives them various superhuman abilities. Any human that has their DNA infected above 50% turns into a Gastrea. However, an exception to this are the Cursed Children, who keep their human physique and possess superhuman abilities, despite the fact the Gastrea Virus has not corrupted them above 50%.[3]


High Stage Gastrea

Multi-Stage Gastrea.

There are five stages to a Gastrea, with Stage I being the weakest and Stage V the strongest. A Stage I Gastrea has been said to be easily dealt with by a lone team composing of a Promoter and Initiator. Rentaro Satomi explains that Stage I Gastrea have only one ability, being the factor which is prominent to their body shapes; e.g. a spider type that is a Stage I cannot possess flying capabilities. However, Stage II Gastrea can have more than one ability such as flying. Stage III and Stage IV Gastrea have been stated to be immensely strong and cannot be compared to a Stage I.[4] Such feat is proven when Rentaro and Enju quickly make an escape when confronted by a Stage IV Gastrea instead of confronting it.[5] Stage V Gastrea surpass Stage IV Gastrea, with the power to destroy the world. However, there are only eleven Stage V Gastrea, otherwise known as Zodiac Gastrea. A normal Gastrea can only grow to Stage IV, while method of creating Stage V's is unknown. Monoliths, which force Gastrea to stay away from the protected area, are said to be no match for the power of a Stage V Gastrea.[6]


Evolutionary Jump is the name Sumire Muroto gives to the Gastrea Virus' ability to give the host a new and unknown ability on top of their original power,[7] such as a jumping spider gaining the ability to knit its web into a kite,[8] and gliding through the air.[9]Aldebaran, a Stage IV Gastrea was capable of using pheromones to control and lead other Gastrea like an army. It was also capable of regenerating at an incredible speed, becoming nearly immortal. Pleiades, another Stage IV was capable of shooting mercury in the form of a "spear of Light".

Known Gastrea[]

Gastrea Type Stage Name
Humanoid Gastrea N/A N/A Humanoid Gastrea
Mouse Gastrea N/A N/A Mouse Gastrea
Bee Gastrea N/A N/A Bee Gastrea
Giraffe Gastrea N/A N/A Giraffe Gastrea
Spider Type Gastrea Spider I Sumiaki Okajima
The Original Gastrea Spider I Original Gastrea
Crocodile Gastrea N/A II Crocodile Gastrea
Shark Gastrea N/A II Shark Gastrea
Horseshoe Crab Gastrea N/A II Horseshoe Crab Gastrea
Lizard Gastrea Bird-Lizard IV Lizard Gastrea
Fly Gastrea Bird-Insect N/A Dragon Gastrea
Insect-Plant Gastrea Insect-Plant III Firefly Gastrea
Aldebaran Unknown IV Aldebaran
Pleiades Unknown IV Pleiades

Battles & Events[]




  1. 1.0 1.1 1.2 Black Bullet Light Novel 3: The Destruction of the World By Fire (pg 89-92)
  2. Black Bullet Manga: Chapter 1, Pages 1-4
  3. Black Bullet Manga: Chapter 3, Pages 20-22
  4. Black Bullet Manga: Chapter 2, Page 52
  5. Black Bullet Manga: Chapter 10, Pages 7-8
  6. Black Bullet Manga: Chapter 9, Pages 23-24
  7. Black Bullet Manga: Chapter 3, Page 22
  8. Black Bullet Manga: Chapter 8, Page 18
  9. Black Bullet Manga: Chapter 8, Pages 19-20