A "side story" film centered on Onaga Terukuni (Kyan Yutaka), the Captain of Yuusei Group, a subsidiary of the Kawatani Family. A legendary assassin is released from prison, and Teru is charged by Himuro (Motomiya Fujikaze) and Tamura (Yamaguchi Yoshiyuki) to welcome him back. But who he meets appears to be a senile old man who may need more help than he realizes ...
Unfortunately the movie Unification of Japan Gaiden: Kawatani Family - Jiro the Outlaw Assassin is not yet available on HBO Max.
| Directing | Hiroyuki Tsuji | Director |
| Writing | Keiichiro Murata | Screenplay |
| Crew | Masakazu Oka | Cinematography |
| Sound | Tsutomu Yamaguchi | Music |
