Ichi Shintarō Katsu is being taken to Doyama, with all expenses paid by an employee of the crime boss Boss Hikozo, who promises only a meeting and no obligation to act. On the road, his guide is killed by rivals who overheard their plans at a tea house, and Ichi ends up taking matters into his own hands, dispatching the attackers and even the husband of a wary bystander named Hisa, who witnesses the brief confrontation. After this, the two part on uneasy terms, the encounter leaving Ichi with a cool sense of detachment.
That night, a group of samurai shadows passing figures on the road, seeking a girl. The mortally wounded man they leave behind asks Ichi to protect Mitsu, a young woman whose life is in danger, and to escort her to Edo so her family can shield her. Ichi soon finds Mitsu—a remarkably well-dressed girl hiding in a shed—yet the situation grows complicated as two men come after them; Ichi defeats them, but one escapes. Mitsu explains that she is hunted because she stabbed the local lord in the face with her hairpin when he tried to assault her, sparking a broader pursuit.
They reach an inn where Hisa is staying and where Jingorô—the man who hired Hisa’s husband—also appears. Jingorô is keen to learn more, and Ichi, who is short on cash, tricks the proprietress by offering to provide massages to earn money for the room. Jingorô agrees to gather information, and Ichi orders Mitsu to stay put in their room. Hisa, aware of the danger, slips away with Mitsu while Ichi, who denies being Zatoichi, shows a sharp, almost reckless confidence—grabbing a sword, disarming the would-be attacker, and delivering a powerful massage that leaves the room in disarray.
Back on the road, Mitsu and Ichi grow closer. Mitsu thanks him for the hardships she has endured, saying they’ve brought them together. At one point, Mitsu playfully wipes her mouth on his face, and he, in a moment of protectiveness, restrains her hand before dispatching three attacking samurai. In the next town, Mitsu asks Ichi to visit her family, and he reluctantly confesses that, if he stays, he might never be able to leave her. She smiles, delighted by the confession, and even in the palanquin she asks him to come along.
As they drift toward the river crossing by boat, Ichi overhears that the two bosses—tension mounting between Hikozo and Tomegoro—are close to a clash. Tomegoro travels to Doyama to press his alliance with Hikozo, while Ichi decides to confront their dangerous coalition. Hikozo makes a bold offer of 20 gold ryō, tempting Ichi away from his usual fee and toward a definite outcome, especially since Matsu, the young man who serves Ichi sake, reveals his love for Mitsu.
Hisa and Jingorô’s men seize Mitsu on the road and drag her to Boss Tobei’s camp, intending to use her to manipulate Ichi. Hikozo launches a dawn raid by boat, and Shimozuma moves to pull Mitsu from danger, despite Hisa’s protests that taking a girl to a fight is wrong. Tobei agrees to let Mitsu call out, and he pressures Ichi to withdraw, even offering to return the money and to work with him to kill the two rival bosses on the other side—Tobei’s main objective.
Ichi dives into the fray, isolating Tobei, Hikozo, and Tomegoro, and he eliminates all three. The panic spreads as others scatter in the street. He then tells Matsu to leave, and Mitsu, unharmed and with Hisa’s apparent aid, leaps back into Ichi’s arms. Tobei’s forces arrive with Jingorô, whom Ichi condemns as deserving death, and they threaten him. Ichi gives money to Matsu, who begs to escort Mitsu to the ferry; as they prepare to depart, he hesitates, almost returning Mitsu’s kerchief before deciding otherwise. The final violence erupts as Ichi kills Jingorô and fends off any who approach.
Waiting on the road, Matsu realizes Mitsu is the girl Ichi spoke of with such fondness, and that Ichi’s money was a signal of his intention to part ways. The movie closes with Ichi walking alone along the road, leaving Mitsu and her future behind as the journey continues.
