Jack is a minor character of Ginga Densetsu Noah.
Ginga Densetsu Noah
Back then, during the war against Mosnoon, Jack and his friends Hikaru, Munechika and Tora wanted to join the Ōu Army to help them in the fight. But half a year after the war, they still didn't returned home. Noone out of the Ōu Army remembers their names.