In
Thailand,
Danish businessman Phillip Eppermint arrives to check on his new factory filled with child laborers. After a young boy named Quang accidentally uses his scarf to create a checkered
ninja plush doll, Eppermint brutally beats the child to death. At that moment, lightning strikes, causing the doll to be possessed by the spirit of a deceased ninja. As the Checkered Ninja ends up on a Danish cargo ship, he is picked up by Stewart Stardust, who gives the doll to his nephew Alex Stenstrom as a birthday present. At school, the ninja defends Alex's friend, Odysseus, from a bully named Glenn using Alex’s voice. After school, Alex learns that the doll is alive after he insults Glenn. Glenn chases Alex throughout
Albertslund and the doll quickly gets rid of him and the two quickly become friends. The ninja promises to help Alex in exchange for him unknowingly helping him get revenge against Eppermint using his lost credit card as a lie to return it to him. Alex realizes that Eppermint shares the same last name as his crush Jessica, then learns from his mother that Jessica’s dad is also called Phillip, so the ninja makes sure that Alex is invited to Jessica’s upcoming party on Saturday. After Alex’s stepbrother Sean, attempts to tell everyone about his crush on Jessica, the Ninja, using Alex’s voice and the school intercom, confesses Alex’s love for her to the whole school. Alex and the Ninja challenge Glenn to a fight on the same day as Jessica’s party. Choosing the playground for the fight, Alex and the Ninja build traps to ensure Alex’s win. On the night before the fight, Alex asks the doll if he is a real ninja, to which he responds by telling him about ninja clans that lived in
Iga Province and how the
samurai were sent to massacre them. A ninja named
Taiko Nakamura was given the mission of protecting the clan’s children whilst fleeing the province. However, one of the clan members betrayed Nakamura, informing the
Nobunaga soldiers to Nakamura’s hut. Nakamura killed most of the soldiers, but they burnt down the hut, killing the clan’s children. Enraged, he vowed for vengeance in exchange for his soul, committing
seppuku. His soul left his body, killing the traitor, and went on to become a wandering spirit that dedicates himself to protecting children. On the day of the fight, Alex wins, gaining him popularity and causing Jessica to invite him to her party. At the party, Alex and the ninja confront her father, actually not who the ninja is looking for as he spells his last name ‘Eppermynt’. Eppermynt gives Alex and the ninja Eppermint’s address. The ninja wants Alex to leave the party to go to Eppermint’s house but he refuses, causing the ninja to embarrass him in front of everyone. Alex is forced to join after the ninja insults Jessica using Alex’s voice in which she kisses Odysseus instead, upsetting Alex. The two arrive at Eppermint's house where the ninja unsuccessfully attempts to kill him. Alex realizes that the ninja is actually Taiko Nakamura. When Alex refuses to help him, Nakamura attempts to murder Sean after Alex wished he was dead earlier. This makes Alex seem insane, causing him to be imprisoned in an asylum. There, the two strike a deal to bring down Eppermint without killing him. Visiting Stewart, he gives them the number of a drug dealer who gives them a kilogram of
cocaine. Alex inserts the cocaine into Nakamura’s body, intending to frame Eppermint for possession of illegal drugs, and follows Eppermint to the airport where Alex and Nakamura emotionally bid farewell. As Eppermint arrives in Thailand, Nakamura jumps onto him. Police subsequently find Eppermint carrying the cocaine-stuffed doll. Nakamura’s spirit leaves the ninja doll and Eppermint is promptly arrested. Back in
Denmark, Alex finds out that before departing, Nakamura sent Jessica a voicemail using his voice, apologizing to her and the two, and they start a romantic relationship. That night, Alex watches news about street criminals and, inspired by Nakamura, becomes a vigilante, dedicated to protecting Albertslund. ==Cast==