Kaiju

Kaiju (怪獣) are a type of large, generally amphibious creatures genetically engineered by the Imperial Army Divison 954 as biological weapons of mass destruction. Designed for psychological warfare and mass destruction, Kaiju are engineered to be extremely durable and destructive, and they typically stand several stories high.

History
Kaiju were the brainchild of Ishirō Honda, an Imperial Army soldier. After being the sole survivor of a Makara attack on Hidaka, Honda became obsessed with the giant creatures. He eventually spearheaded a project to control the Makara as a weapon of war using pheromones and neural implants. The Bakufu took notice of his project. Imperial Army General Haruo Nakajima joined forces with Honda, giving and sharing with him the idea of generating their own monsters to fight the enemy. Together they formed Division 954 in 2314.

Deployment
Kaiju hatch from eggs which are deployed into the target area by special forces, usually situated in difficult-to-access areas such as underwater or in dense jungle. The newly-hatched creature rapidly matures within a few days and is already programmed to seek out the closest mass of bio-signatures, ensuring the Kaiju attacks large cities or military bases.

Lifespan
In order to prevent unleashed Kaiju from becoming a threat to friendly forces, Division 954's geneticists ensure that every unit has a lifespan limited to mere weeks or even days.