Shimazaki in the Land of Peace 1

After surviving a terrorist incident as a child, Shingo Shimazaki was forced to join the League for Economic Liberations' revolutionary army. Now, thirty years later, he's back in Japan and trying to assimilate to a normal life. His Japanese may be awkward, and his grasp of ordinary tasks a little weak, but he has all the combat and surveillance training of a green beret. There are many kindhearted souls who want to help him—and a few not so kind ones who will do anything to stop him.

Volume 1 of the Shimazaki in the Land of Peace manga series by Gouten Hamada.