In the futuristic city of Grainland, a girl named Mai Su is living an ideal life with her parents, until an argument between them ends with her father leaving the family. Over the next several years, her mother Molly copes with the separation by buying several highly advanced robots called Q-Bots, unintentionally leaving Mai feeling neglected and alone. This leads to Mai rejecting all robots and making her an outcast among her peers, as robots soon replace everything, from police to teachers.
Years later, Mai is now a adolescent teenager and Molly is almost completely oblivious to how her daughter feels. She and Molly head out to the launch event for the Gen 6 Q-Bots. Mai, disinterested in the whole ordeal, decides to leave the line on an escalator and destroys a robot that was pestering her. After being cornered by security Q-Bots, she decides to escape to a nearby chute for the smaller robots, entering in Dr. Tanner Rice’s secret lab where he has developed a robot of his own: Project 7723. After being annoyed by his assistant Q-Bot Alfredo, Dr. Rice leaves the lab in which Mai decides to investigate. While inspecting 7723, she accidentally activates him. Mai eventually gets caught by a security Q-bot and brought back to the launch, leaving her backpack behind.
During the launch, IQ Robotics’ charismatic CEO Justin Pin introduces the newest model of Q-Bots, “Gen 6.” After offering free Gen 6 models to everyone that showed up to the presentation, Justin and his enormous, intimidating robot, Ares head down to the manufacturing factory and meet with Dr. Rice, who shows reluctance to releasing the Gen 6 Q-Bots. Alfredo then privately reveals to Rice that 7723 has left the secret lab and Rice panics.
7723 eventually escapes the building to locate Mai and return her backpack to her. A security bot tries to stop him and he slices the bot in half in response. Now on the highway, 7723 is confronted by various security bots trying to stop him, but are unable to capture him due to his advanced weapon systems. The security bots then fire missiles at the bridge, causing the bridge to break and send 7723 falling into the lower parts of Grainland. Waking up several hours later, 7723 discovers that he has damaged his core memory functions, resulting in him having only enough storage for three days worth of memory.
Back in school, Mai is playing soccer by herself until she hits another girl named Ani, who happens to be sitting nearby. They are then confronted by Greenwood, a bully who insults Mai about her dead father. Upset, Mai kicks her soccer ball right into Greenwood’s face. Greenwood then orders her and her friends Q-Bots to attack her. Mai returns from school, upset, and Molly attempts to cheer her up but fails to recognize that robots don’t help with Mai’s problems. Mai then heads to her room while Molly attempts to find companionship with her Q-Bot.
7723 then arrives at Mai’s house, he returns the backpack, but Mai is still irritated with him. After being attacked by her robotic toothbrush, 7723 fires a laser at the toothbrush. Fascinated by 7723’s hidden weaponry, Mai allows 7723 to stay in her garage. It is then revealed that in order to further delay the event of him from losing his memories and shutting down, he must delete excess memories in order to create space. Meanwhile at IQ, Justin confronts Dr. Rice about 7723. He tells him to not to worry about fixing an error with the Gen 6 that has them explode when close to a human.
Mai then returns to the soccer field with 7723 by her side to get revenge against Greenwood for the following day. Greenwood sends one of the robots to attack Mai, but 7723 easily destroys it. Mai, extremely interested in 7723’s abilities, takes him along for misadventures which mostly involve destroying robots and the two bonding. 7723 struggles with choosing which of these memories to keep and forget.
During a talk show, Justin is addressed with 7723’s actions on the highway, who bears his company’s logo. He passes it off as a knockoff robot that was found and deactivated shortly after, until he is shown new events which involve Mai and 7723’s misadventures and destruction of Q-Bots, to which he claims that the robot is not his.
After another day of mischief, Mai and 7723 return home in which 7723’s program reveals that he only has 18 hours of memory storage left. He reveals to Mai that he cannot exceed 100% of memory storage or else he will shut down and reboot completely. Dr. Rice is then threatened by Justin after the incidents with 7723. He is then tasked with finding him. Rice reveals that he can see what is happening through every active Q-Bot’s eyes in hopes of finding 7723. 7723 then tells Mai he wants to play baseball instead of their usual routine. Mai exclaims that what they do is justice for how robots have negatively impacted her life. Dr. Rice then proceeds to look through the Q-bot footage, which reveals that 7723 does not enjoy the mischief that Mai is making him do.
The next day at school, Greenwood continues to bully Ani, in which Mai takes 7723 again to once again get her revenge. 7723 is now reluctant to commit mischief. After trapping Greenwood, Mai orders 7723 to hurt Greenwood with his energy cannon, which he refuses to do. Just as Mai was ready to hit Greenwood in the head with the bat, Greenwood starts crying and Mai realizes what she is doing is wrong and is no better than Greenwood. Later into the night, when choosing which memories to delete, 7723 decides to delete his weapon control system until he has to reset.
7723 finds out that Mai has run away from home. He eventually finds her by a hill and has made a colorful light that creates a picture of Mai’s family to project on the night sky. When Mai reminisces over the happy life she had before her father left her home, the two forgive each other and continue to watch. Mai then returns home to find Dr. Rice waiting for her. He inspects 7723 and reveals he can fix his memory storage but this will delete all of his existing memories. Before he can do that, Justin arrives with Ares to take Dr. Rice away. Rice tries to appeal to Justin’s sense of humanity and their long past friendship but is ignored. Justin then reveals his plans to kill the entire human race. He then orders Ares to attack and 7723 then proceeds to fight without his weapons while Mai tries to attack Justin who displays some robotic mannerisms. While trying to escape Mai’s mother is kidnapped by Justin. The duo then escapes into the sewers, which Mai is enraged by 7723 deleting his weapons function and allowing her mother to be kidnapped. Mai then leaves 7723 behind, crying.
At the IQ headquarters, Mai has infiltrated the building, determined to save her mother. She is then reunited with 7723, still angry about previous events. As they fight security bots side by side, the two reconcile and head onto Dr. Rice’s lab. There he reveals that her mother is bait in a trap for them and tries to fix 7723. He is suddenly interrupted by Ares and Justin, who kills Rice by vaporizing him. While listening to Justin talk, Mai quickly discovers something is off about him as his movements begin to mimic Ares’s. Eventually, Ares then explains that he killed the real Justin after he created him and has been using his cybernetically altered body as a puppet. Ares reveals he plans to make the world perfect by exterminating the human race, ending all conflicts in the process. 7723, Ares, and “Justin” fall through a window, landing in a crowded soccer field where they all have a drawn-out fight.
Mai successfully reconciles with her mother, and Ares unknowingly confesses everything on camera with a whole stadium of people watching. Mai manages to tell the public the Q-Bots are bombs and knock out Justin’s eye, to which he openly confesses everything. He attempts to kill Mai until her mother beats him up. Back on the field, 7723 tries to stop Ares, but to no avail. Mai begins helping the people evacuate the stadium, saving Greenwood from her exploding Q-Bot. Mai ends up taken hostage by Justin on the roof of the stadium to taunt 7723 while he fights Ares. However, Greenwood returns to help free Mai and she and Justin fall off the building. 7723 initiates his system reboot to reacquire his weapons and saves Mai from falling. As he’s fighting, he’s slowly losing all the memories he shared with Mai. After defeating Ares in orbit, the two robots crash into the surface and 7723 prepares to finish off the former, who is now heavily dilapidated. However, his reboot finishes before he can fire and he shuts down. Mai arrives to find 7723 mostly intact but inactive, but Justin arrives having survived the fall and attempts to kill 7723, but Mai manages to decapitate Ares, destroying them both. 7723 soon reactivates, but has none of his past memories of Mai whom he loved and greets Mai the same way he did the first time they met.
Sometime later, Mai is shown to be hanging out with Greenwood, Ani, and her friends, along with 7723. The movie ends with all of them creating new memories and playing soccer together while 7723 even begins to subconsciously remember some of his old ones, including the fact that he and Mai would always look out for each other.