Toratsugumi: Tsugumi Project

In the far future, a soldier named Leon is taken from his family on a trumped-up charge and dropped into a suicide mission: Recover a dangerous weapon from a deadly place — a place ruled by huge, irradiated, mutated monsters — a place once known, 200 years ago, as Japan. He and his teammates aren't expected to survive this place. One of the scant pieces of information they have is the weapon's name: Tsugumi.
(Source: Kodansha USA)