Took me a while to find it, because I kept finding the chinese version, and those chinese sites didn't show much of the japanese title. All I know is that the Chinese title is 父子神鷹.(I can't romanize it, sorry.) Or maybe that's the japanese title, I don't know, I can't find any other results. o__o; somebody correct me if I'm wrong. The manga is also titled as Grapple Guys in other countries. It was publish at around.... 1996 or so..