Raizo, a skilled assassin portrayed by Rain, is brought up within the ruthless Ozunu Clan, where he undergoes intense and brutal training by his "father," Lord Ozunu, played by Sho Kosugi. As a child, Raizo faces harsh punishment—whippings and cuts—whenever he falters, alongside constant encouragement to harm his fellow ninjas for the sake of their training. The only glimmer of kindness he receives comes from a kunoichi named Kiriko, played by Anna Sawai.
As they grow into adulthood, a romantic bond blossoms between Raizo and Kiriko, but her yearning for freedom from the clan ultimately weighs heavier on her heart. During a tumultuous night, Kiriko takes the brave step to escape, urging Raizo to join her. Despite their affectionate farewell kiss, Raizo chooses to remain. Kiriko’s attempt at liberation ends tragically as she is captured and, branded a traitor, executed by her brother Takeshi, portrayed by Rick Yune, who thrusts a katana through her heart. This horrific event ignites a flame of resentment and doubt within Raizo towards the Ozunu Clan.
After completing his first assignment, Raizo is given orders by Lord Ozunu to dispose of a traitorous kunoichi, mirroring Kiriko's fate. Defying his master, Raizo retaliates and narrowly escapes, plunging into a nearby river and surfacing anew with a resolve to thwart the clan’s plans. Taking refuge in Berlin, he rents a modest apartment, honing his skills as he awaits his moment to strike.
Meanwhile, Europol agent Mika Coretti, portrayed by Naomie Harris, is on the trail of illicit funds tied to high-profile assassinations, tracing them back to the Ozunu Clan. Disregarding orders from her superior, Ryan Maslow, Mika digs deeper into her investigation. When the clan discovers her inquiries, they attempt to eliminate her; however, Raizo intervenes and saves her life.
Mika persuades Raizo to enlist Maslow's protection, but during their meeting, Raizo finds himself ambushed by a task force. Feeling deceived, Mika is torn, yet Maslow secretly reassures her of his loyalty, gifting her a tracking device for emergencies. As the Ozunu ninjas infiltrate their base, chaos ensues, leading to a frantic rescue mission where Mika helps Raizo escape. In the heat of battle, Raizo sustains grave injuries while fending off pursuers, and with Mika's assistance, they manage to evade immediate capture. However, Raizo’s wounds prove severe.
In a moment of desperation, Mika implants the tracking device into Raizo, who is soon recaptured by the clan and brought before Lord Ozunu for judgment. Hidden within a steel locker, Raizo employs his healing techniques to mend his wounds before facing his father, who, enraged by Raizo's insubordination, decides on a public execution.
The situation takes a dramatic turn as Europol's Special Forces, led by Maslow, storm the clan's hideout and engage in a fierce showdown with the ninjas. During a climactic confrontation, Raizo and Takeshi clash in the burning training hall, culminating in Raizo overcoming his brother. The duel escalates as Raizo confronts Lord Ozunu. Just when it seems that Raizo might not prevail, Mika intervenes, shooting Ozunu to save him, but is met with a devastating blow when Ozunu retaliates and stabs her.
In a moment of emotional turmoil, Raizo taps into his skill of 'shadow blending' and ultimately vanquishes Ozunu. Although Mika appears fatally wounded, her unique anatomy—having her heart on the opposite side—miraculously saves her life. As Europol agents evacuate from the destroyed compound, Raizo chooses to remain behind, symbolically climbing the wall that Kiriko had scaled years prior, finally embracing his newfound freedom as he gazes out at the vast countryside. A smile graces Raizo’s face, leaving the audience with a poignant sense of hope and liberation at the film's close.
