ijin lived 5 years in the camp then he ran away because he couldn't follow an oder about killing an innocent civilian then he did 4,5 years mercenary work when he worked there he got some memories back (only his name and maybe some more but not much) he met the lieutenant when he saved him (what was a request when he was a mercenary) and than he got more of his memories back six months later the lieutenant found his family and he went back to his family. This is kind of what happened i think.