Yamaguchi is a guy who works at bar in the slum Trench Town in Violence Jack Harlem Bomber. He recognizes Violence Jack and tells Sabu to tell Slum King that Jack is at his place but saburefuses since his grampa said that Jack fights for weak people like him. Yamaguchi tells him that they'll get wacked if they don't tell them that Jack was with them and he goes off to tell them off screen. When Rose and friends get there, Jack is gone and She whips Yamaguchi and leaves as Sabu hides behind a wall but in a doorway. When trench town is under attack by Laser he realizes that its Jack's presence that makes everyone go nuts. And then...he died... from getting shot up by a machine gun.
He was voiced by Masashi Hirose who was Mobston in One Piece Z(like it wasn't enuff a rip off of DBZ?!), Shireikan in Slayers, Jimushi in the Tv ninja Scroll, Saburota in Black Lion, Stinger in Getter Robo Armageddon, Ryusen in Sword for Truth(A cr-ppier ninja scoll and black lion), Tha in that 80s Jungle Book Anime, Taihei Shibaki in Violence Jack Evil Town, Kanta's dad in My Neighbor totoro(And he b0ned all those chicks in Violence Jack!!), Syncam Personnel Managar in LILY C.A.T(Which was quite good), Rikishiman in Kinnikuman and Ramba Ral in Mobile Suit Gundam stuff.
In the dub he was voiced by Bob Johnson who according to IMDB was another name for Colin Bruce who was Sakomizu in Genocyber, Major Lennox in The Secret Garden(The 93 ver. Not the moving 60s ver), Beard / Cop / Mafia in Cyber city Oedo 808(Ja c-ck suckin sunnova b--ch!!), Tetsuya in Violence Jack Hell's Wind, Kurata in Violence Jack Evil Town, Doctor in Devilman:Demon Bird Sirene, Reijiro Fudo and Dancerin Devilman:The Birth, Walla in Angel Cop(F--k and P-ss!!), Yan n Crying Freeman(Slave!!!), Cop / SWAT / Tech in Appleseed and Taylor in Charioys of Fire(Wait, that one was Good!! wtf!! He started out well and devolved into violent p0rn0!!)