Raizo Yamaguchi (Rain) was raised by the Ozunu Clan, to become their next successor of the clan. As a child, Raizo experienced severe training under the guidance of his "father", Lord Ozunu. He was whipped and/or cut whenever he failed and was encouraged to hurt his ninja kin for their failures during their training. The only kindness he ever received was from Kiriko (Kylie Goldstein). As they grew older, Kiriko (Anna Sawai) and Raizo developed a romantic bond, however Kiriko's desire to leave the Ozunu clan for freedom was greater. One stormy night, Kiriko decided to escape from the Ozunu. Kiriko encouraged Raizo to join, but he decided to stay. They kissed and she then climbed over the wall to freedom; she was caught and brought back by her ninja kin. Branded as a traitor, Kiriko was executed (a katana through her heart) by her elder ninja brother Takeshi (Rick Yune). When Kiriko died, Raizo begins to harbor resentment and doubt towards the Clan. When he completed his first hit, Lord Ozunu told him to execute an escaped kunoichi like Kiriko. He rebelled against Lord Ozunu by slashing his face with is blade-chain (kyoketsu shoge) and fought against his ninja kin. Barely surviving his battle, he survived by falling into a nearby river. Raizo recovered and began interventions by foiling recent hits by the Ozunu. While staying in Berlin and waiting for the Ozunu's next move, Raizo rented a small apartment where he secretly continued to refine his training until it was time to act. One day, while washing his clothes, he was approached by an attractive Asian woman who asked him to help her fold her sheets. Raizo exposed her as a kunoichi and she attempted to kill Raizo; Raizo won and hid her remains in the washer machine. By the time the owner came out, he only found her bloody remains in rinse cycle. Meanwhile, Mika Coretti (Naomie Harris) is a Europol agent who investigates money linked to political murders and finds that it is linked to the Ozunu Clan. She defies her superior, Ryan Maslow (Ben Miles), and retrieves secret agency files to find out more. The clan, finding out about the investigation, attempts to assassinate her, but she is rescued by Raizo. Mika convinced Raizo to meet with Maslow for protection and evidence against the Ozunu, but Raizo was intercepted by a task force for interrogation. Mika felt betrayed that Maslow would trick her that way, but Maslow assures Mika (in secret) that he's still on her side and gave her a tracking device for emergencies. Mika was warning Maslow the dangers of keeping Raizo when the Ozunu ninjas infiltrated their secret base and began killing all officers. Mika freed Raizo and he lured the ninjas away as Mika tried to escape. Raizo killed and fended off as many ninjas as he can while Takeshi continues to trail him. Raizo and Mika managed to escape the fight, but Raizo had suffered mortal wounds around his stomach, however he insisted no hospitals and only rest in a private area. Mika then implanted the tracking device into Raizo. Unable to fend against the Ozunu, she hid outside the hotel until special forces arrive to help her. By the time they arrived, Ozunu ninjas have recovered Raizo and decided to send him back to their base for Lord Ozunu for prosecution.

While hidden inside a steal locker, Raizo spent all this time using his healing techniques to heal all major injuries before being reunited with his "father". Lord Ozunu had Raizo tied to a stake, ready for execution and set as an example. Raizo angered Lord Ozunu more by being defiant to the end. Lord Ozunu struck against Raizo's internal organs when he spat out the tracking device. Euro-special forces lead by Maslow stormed the hidden Ozunu base and killed most of the ninjas in the court yard. Takeshi and Raizo face each other in the burning Ozunu training hall. Raizo, victorious confronts his adoptive father Lord Ozunu. While Lord Ozuno initially has the upper hand, Mika, fearing for Raizo's life, distracts Lord Ozunu, shooting him with her pistol. Before Raizo can recover, Ozunu stabs her in the heart. Emotionally ravaged, Raizo uses the 'shadow blending,' technique for the first time, and defeats and kills Ozunu. Mika, although seemingly fatally wounded, is saved by a quirk of her birth: her heart is on the opposite side of her chest, in the same fashion as the tattooist from the introduction. Mika and EUROPOL leave the destroyed Ozunu compound, while Raizo stays behind. Symbolically, he climbs the same wall Kiriko did all those years ago, and looks out at the surrounding countryside. Recognizing his freedom for the first time in years, Raizo smiles, ending the film.

• Rain portrays Raizo, one of the world's deadliest assassins.
  • Yoon Sungwoong portrays Raizo as a child, and Joon Lee portrays Raizo as a teenager.
• Naomie Harris portrays Mika Coretti, a Europol agent.
• Rick Yune portrays Takeshi, the leader of a team sent by the Ozunu Clan.
• Ben Miles portrays Ryan Maslow, Mika's Europol superior.
• Sho Kosugi portrays Lord Ozunu. Leader of the Ozunu Ninja Clan.
• Anna Sawai portrays Kiriko, Raizo's love interest.
  • Kylie Goldstein portrays young Kiriko