That_Homestuck
It all started in Tokyo, Japan in 1957, before Himitsu was born. Operation Empire started, thus beginning a series of government experiments of 'human weapons', creatures that can control the battlefield itself. However, after time the testing was shut down for the sake of the public protesters and set the participants free to live among normal people as humans. The lead scientists didn't like that, so they moved their research from U.S.A. to Japan, where they had access to more advanced technology and weaponry to make their own weapons more powerful than before. The creatures were referred to as Homo sapiens telum, a subspecies of Homo sapiens that few people know of in order to support the undercover operation.
Disclaimer: I did take the name The Shadows That Live from the Daughter of Smoke and Bone series