Checkered Ninja

The ninja uses Alex's voice as a supernatural ability to communicate and interact with the world without drawing attention to himself. Since the doll cannot speak on its own, borrowing Alex's voice allows him to defend Odysseus from bullies, confess Alex's feelings to Jessica, and manipulate situations to further his revenge plan while remaining undetected.

The ninja first demonstrates this ability when he uses Alex's voice to defend Odysseus at school, shocking the entire student body.

The ninja exists as a spirit bound to the doll, which limits his physical capabilities. He needs a living person to execute his plan because he cannot physically travel to find Eppermint, access his location, or carry out the complex scheme involving the credit card ruse and later the cocaine frame. Alex serves as his unwitting accomplice and physical extension in the human world.

Taiko Nakamura was a legendary ninja protector from Iga Province in Japan. After samurai warlord Nobunaga's forces massacred his clan, including the children he was sworn to protect, Nakamura sealed his soul into the doll in exchange for vengeance. He became a wandering spirit dedicated to protecting children, but his quest for revenge against those who harm the innocent drives his actions throughout the film.

The ninja shares this legend with Alex the night before the party, explaining the origin of his soul-sealed mission.

Earlier in the film, Alex jokingly wishes that Sean would die after Sean embarrasses him. When the ninja (who has supernatural perception of people's true desires) perceives this wish, he attempts to fulfill it by attacking Sean. This moment reveals the ninja's dark nature and willingness to kill, shocking Alex and causing him to be institutionalized when he appears unstable.

Alex's casual wish for Sean's death planted the seeds for this violent confrontation.

From the asylum, Alex and the ninja recruit Stewart, who provides a drug dealer's number. They obtain a kilogram of cocaine and inject it into the ninja doll's body. Alex then plants the cocaine-laden doll on Eppermint at the airport. When police search Eppermint in Thailand, they find the doll with the hidden cocaine, leading to his arrest for drug possession.

The plan was devised after the ninja's assassination attempt at Eppermint's house failed, requiring an alternative method to bring him down.

The ninja, using Alex's voice, insults Jessica in front of the party guests, humiliating Alex. Hurt and confused by this betrayal, Jessica turns to Odysseus, who had been supportive throughout the story. This moment devastates Alex and creates tension between him and the ninja.

The ninja's manipulation of Alex's social life was always self-serving to keep him focused on the revenge mission.

After witnessing Nakamura's dedication to protecting innocent people and seeing the criminal elements in Albertslund on the news, Alex feels inspired to follow Nakamura's example. He decides to become a vigilante to protect his community, using the skills and lessons learned from his partnership with the ninja.

The ninja's own mission to protect children and punish those who harm them directly influenced Alex's decision.

Eppermint is portrayed as a ruthless businessman who beats Quang to death after the boy accidentally uses Eppermint's expensive scarf to make the checkered ninja plush. The murder is brutal and senseless, establishing Eppermint as the film's villain and providing the ninja with his motive for revenge.

This violent act occurs immediately before the lightning strike that possesses the ninja doll, linking Eppermint's cruelty directly to the supernatural events that follow.

The ninja wants Alex to leave the party and pursue Eppermint immediately, but Alex refuses because he wants to enjoy the celebration and his social success. Using Alex's voice, the ninja insults Jessica to sabotage Alex's social standing, forcing him to leave in shame and continue the revenge mission.

This manipulation shows the ninja prioritizing revenge over Alex's happiness throughout the film.

At Jessica's party, the ninja confronts her father expecting to find the villain Phillip Eppermint. However, he discovers the father is spelled "Eppermynt" - not the same person. This comedic twist sends the ninja and Alex on a new path to find the correct Eppermint, adding a plot complication.