Gate Keepers - Open the Gate (Vol. 1) (Geneon Signature Series)
Set in Japan, circa 1969, GATEKEEPERS finds unconventional guerilla tactics being used by an unknown group of soldiers, known only as the Invaders, who are apparently trying to slow Japan's recovery from WWII. Unfortunately, these guerillas seem to be impervious to traditional means of fighting, panicking many army and government officials. However, soon a new type of hero is discovered among the teenage population of Japan who call themselves the Gate Keepers. Endowed with the ability to open gates to other dimensions, these teenage heroes are Japan's only hope for defeating the guerilla menace.