Masato

Two contract killers cross paths in the middle of the same job and realize they are childhood friends. (imdb)

Minor Ryo Narushima (Shawn Yue)is send to youth-prison for murdering his parents where he learns karate under the tutorship of Kenji Kurokawa (Francis Ng). After Ryo is released three years later, he wants to put his karate to use. His aims to become the champion in a brutal freestyle fighting league.

There's a Macguffin puzzle box with some magic goo in it, but only one guy named Copy knows how to open it. The Koga ninja have the box and want the goo, but the Iga ninja are protecting Copy to prevent the Koga from using the goo to poison people, leading to lots of fights.