Simon's back arches on the hospital bed as the blood courses through him. His eyes shine brightly, and his chest begins to glow even more intensely. Simon remarks that Conor's blood is remarkably accelerating his healing process. The shadow covering half of Simon's face dissipates, unveiling his complete face, now glistering. Removing all the tubes from his body, Simon's wounds heal quickly. Feeling significantly better and more robust, he calls out Conor's name and ponders about his identity. Employing his shadow magic, Simon transforms his jeans into black ones and dons a misty shadow shirt. Glancing at himself in the mirror, he declares that he is now prepared to meet Mai, exuding confidence in his newfound appearance.
Many years ago, when Mai turned 18, she celebrated her birthday with her boyfriend, Simon. As a couple, they were joyous, and Simon, aware of Mai's captivating appearance, was consistently overprotective. He would unquestioningly do anything for her. Over time, as Simon reached the age of 23, he, Aiden, and their parents found themselves driving home after an extended trip. Seven-year-old Aiden, sitting in the back seat, continuously kicked the driver's seat, prompting his father, who was driving, to instruct him to behave. Simon, waking up from a nap due to Aiden's whining, was urged by their exhausted mother to calm down his younger brother. Simon expressed regret, stating that they should never have spoiled Aiden as a child. Attempting to pacify Aiden, Simon encouraged him to be a good boy. However, Aiden persisted in rebelling and whining, causing frustration among the other family members. Observing the stress Aiden's behavior was causing, Simon wanted him to behave better for the well-being of everyone.
Aiden, persisting in his troublesome behavior, hurls his phone forward, shattering the rearview mirror. This prompts their father to become furious and turn back to yell at Aiden, who, in turn, begins to cry from the scolding. Unbeknownst to them, due to the distraction, they run a red light. Simon, noticing the situation, warns his father about the road ahead. Their father, realizing a car is about to collide with them from the side, swerves to avoid it. Unfortunately, this evasive action causes their car to spin and flip over the guardrail onto the train tracks below. The car crashes upside down onto the tracks, with the front of the car on the tracks and the rear of the car barely away from the tracks. Upon regaining consciousness, Simon finds himself with a bloody head and attempts to move, only to discover that his legs are broken. Turning to survey the scene, he sees Aiden unconscious and severely injured.
Facing his mother's lifeless form, Simon breaks into tears, realizing she has succumbed to the crash. He desperately calls out to his father, who regains consciousness and urges Simon to escape with Aiden. Overwhelmed by the situation, Simon explains that he can't move due to his broken legs. The distant sound of an approaching train amplifies their distress. Simon's father instructs him to crawl, insisting he save himself and Aiden. Grimacing in pain, Simon removes his seatbelt and maneuvers through the wreckage, reaching Aiden's side. His father, expressing remorse for their ill-fated lives and tells Simon to take care of Aiden, Simon then holds onto Aiden, prepares for the imminent collision with the oncoming train. The train attempts to brake, but its speed remains perilously high. The impact tears the car apart, propelling its rear away from the tracks. In the aftermath, Simon lets out an emotional scream, realizing his parents are now dead, their lives claimed by the tragic accident caused by his younger brother, Aiden. Leaving Aiden in the damaged car, Simon painfully crawls away to seek help.
A short while later, Aiden and Simon find themselves in the hospital. Simon, fully conscious now, has casts on both of his broken legs. When Simon turns to his brother, he discovers Aiden in tears, regretting his actions. Mai pays a visit, offering Simon a comforting hug. However, this moment triggers a darker aspect of Simon, as a newfound resentment toward Aiden begins to fester. As the months pass and their health improves, Simon decides to distance himself from Aiden, leaving him in the care of the government. This choice marks the beginning of a downward spiral in Simon and Mai's relationship. After discovering Simon's abandonment of his brother, Mai ends their relationship. Simon, consumed by anger, starts stalking Mai, and his actions take a sinister turn. He secretly kills any guy attempting to flirt with Mai. This pattern of violence continues, leaving Mai distressed and convinced that she is cursed, unaware that Simon is the cause of the mysterious deaths surrounding her.
Simon persistently attempts to rekindle his relationship with Mai, but she consistently rejects his advances. This pattern continues for five years. Mai finds herself in New Berry Town's park, documenting her day for her vlog. She mentions an important interview later but emphasizes an equally important meeting at the park regarding her ex-lover. Suddenly, Simon appears, looking disheveled and sleep-deprived. He pleads with Mai to return to his life, claiming he is nothing without her. Mai, firm in her stance, asserts that she will never be with a man who abandoned his own family. In frustration, Simon blames Aiden for their parents' deaths. Mai counters, stating that Aiden is just a child who shouldn't be left to grow up alone. Simon, growing angrier, is on the verge of revealing a dark secret from the past five years, but before he can, Mai shares a surprising revelation. Aiden, now 12 years old, enters the park. Mai discloses that her intention is to reunite the two brothers. Aiden, expressing remorse, kneels down and admits that the tragic incident that claimed their parents' lives was indeed his fault.
Aiden pleads with Simon, expressing his desire to be a part of his life as he the only family he has left. However, Simon remains adamant, insisting that he wants no one else in his life except Mai. Disheartened, Mai shakes her head and walks away. Simon contemplates chasing after Mai but turns back to see Aiden on his knees, crying with his head bowed. A flashback to his father's words about taking care of Aiden before the train accident weighs heavily on Simon's mind. Reluctantly, he walks back to Aiden, apologizing for leaving him for five years and acknowledging that he'll allow Aiden back into his life. Aiden embraces Simon, Simon then clarifies that this may improve his chances of rekindling a relationship with Mai.
Meanwhile, Mai continues vlogging her day with the camera facing her. Suddenly, the zombie apocalypse unfolds. Mai fends off a zombie attacking an elderly man, but another lunges at her. Simon intervenes, pushing the zombie away and repeatedly stabbing it in the head with a knife. Mai rushes off to the train station, leaving Simon in a dilemma. A zombie jumps onto Aiden, and Simon grapples with the decision of whom to save – Mai or Aiden. After a moment of struggle, Simon chooses to save Aiden, hoping it will increase his chances of winning Mai back into his life.
Simon persists in beheading approaching zombies, shielding his brother from the undead onslaught. To protect Aiden further, Simon places a dead zombie on top of him and instructs him not to move. Despite being bitten on his arms, back, and face, Simon relentlessly dispatches zombies with his knife. Aiden witnesses the gruesome scene as the pile of corpses conceals him from the other zombies. Simon fights through the biting undead, creating a barricade of bodies around Aiden. Simon eventually heads for the train station, where he spots Mai assisting others onto the train. A zombie attacks Mai, causing them to fall onto the tracks. Reacting swiftly, Mai pushes the zombie away as the train inches forward.
Leaping onto the train tracks, Simon dispatches the zombie from behind. Mai observes the multiple bite marks covering Simon's body. Recognizing the danger, Simon urges Mai to leave, assuring her that he will return for her. A swarm of 20 more zombies converges on the train tracks, closing in on Simon. Despite his waning strength, Simon turns around to confront the undead adversaries, delivering strikes against the encroaching horde. Mai, fleeing the imminent danger, boards the back of the train and witnesses Simon becoming overwhelmed by the relentless zombies. Lying on his back, Simon succumbs to the gruesome fate as the zombie horde devours his flesh. Glancing at Mai escaping on the train, Simon smiles. His eyes then illuminate with a magical glow as he undergoes the transformation into a zombie.
Simon's heart erupts in magical light, shrouded by shadow magic that courses through his radiant brain. Fueled by an overwhelming desire to reunite with Mai, he undergoes a transformation, emerging as an A-STAR zombie. Cloaked in shadows, Simon swiftly dispatches the surrounding zombies, his path set toward Old Berry Town. However, the realization dawns that Aiden is crucial for his reunion with Mai. Simon hurries to Aiden's location, extracting him from the lifeless pile of zombies. Aiden, shocked to witness Simon as a zombie, receives reassurance that everything is under control. Simon, now endowed with extraordinary powers, leads Aiden to his apartment building. Clearing the structure of both zombies and humans, he instructs Aiden to remain in his room until his return. Concerned about zombies finding him, Aiden begs Simon to stay but Simon touches him, infusing Aiden's body with his protective shadow magic.
Simon dashes to Old Berry Town, repeatedly rescuing Mai from imminent danger, and even eliminating a few individuals who approached her for assistance. Later, Mai, Xai, and Michael hop into a van, heading toward Robo Mall. Simon employs his shadow magic to lift the van from the horde. As time elapses, Adam experiences an emotional outburst in Old Berry Town. Believing Adam poses a threat to Mai, Simon engages in a fight with him but is ultimately defeated, sustaining significant injuries and losing a considerable amount of magic. Subsequently, Simon returns home and implores Aiden to assist him in locating human bodies for consumption, a process necessary for him to regain his former appearance and restore his powers. During the courthouse battle, Mai plummets from the rooftop, prompting Simon to utilize the remnants of his magic to catch her with his shadow magic.
Since that time, Simon lacked the magical strength required to observe and safeguard Mai. He bided his time in the basement of the apartment building, where Aiden inserts tubes into Simon's body and arranged all the necessary elements to aid his brother. Over the passing months, Aiden captured numerous humans, chaining them up, inserting tubes into their bodies, and extracting their blood. Two years elapsed, during which Aiden amassed a substantial number of humans—over a hundred—for his brother. However, the task became more challenging as there were no more humans left in New Berry Town. To continue honing his shadow magic skills, Aiden practiced on the undead in New Berry Town, resulting in the elimination of all zombies in the area.
Aiden then ventured into Radiant City in search of humans, but his efforts were in vain as he couldn't locate any. He redirected his focus to Old Berry Town, where he observed Duke, Jean, and Kayla spending time together in the park, enjoying their moments. Aiden, struck by the realization of his own loneliness, yearned for companionship. In a sudden impulse, he captured Duke and brought him back to Simon, pleading to have Duke as a friend. Simon, mostly covered in shadow magic, agreed under the condition that Duke assist in cleaning the apartment. Initially, Aiden and Duke didn't hit it off as friends, but with time, their bond grew stronger, and Duke adapted to the routines of the apartment. Duke had an epiphany, recognizing that Simon's obsession with Mai drove him to extreme measures to reunite with her, albeit not in an unattractive zombie form but as an improved version of his former self. Additionally, Duke understood that Aiden shared a similar obsession, feeling bound to help his brother in any way possible, haunted by the belief that he was responsible for their parents' deaths.
In the present time, Simon expresses his desire to meet Conor, but insists on reuniting with Mai first after patiently waiting for so long for this day. As Simon walks down a long hallway, he enters a room adorned with a red carpet leading to a red table. The room is filled with pictures capturing moments from Simon and Mai's past relationship. Simon sits patiently in a chair, while Aiden opens Mai's room and frees her. Mai then tries to escape, however, the shadow figures restrain her. Mai spots Duke and Conor together and pleads for their help. Duke apologizes, and Conor admits to being out of magic power, leaving them to await Frank's potential rescue. The shadow figures escort Mai to the basement, where she stands before a door. As the shadows dissipate, Mai opens the door, revealing the red carpet room. She walks down the hallway, observing the pictures of shared moments with Simon depicted on the walls, and takes a seat across from Simon. With a smile, Simon remarks on the extended wait and how, despite the world's end, they were destined to be reunited. Duke then comes into the room and presents two plates of steak and sets them on the table, bowing before exiting the room.
Simon acknowledges that he and his brother share an unbreakable bond now, having rectified the issue of abandonment that initially led to Mai leaving him. Expressing this newfound strength, Simon politely requests Mai to re-enter his life, claiming to be as perfect and better as ever. In response, Mai questions if Simon was the cause of the deaths of those around her. Simon admits to this and asserts that he alone deserves her. Mai then gratefully thanks Simon for all those times he saved her but she also acknowledges that he took many innocent lives from her, asserting that he doesn't deserve her either. In a shocking move, Mai attempts to end her own life by stabbing the fork on the table into neck. In her internal dialogue, she reflects on possibly not deserving anyone due to the pain she brings to those around her. Witnessing Mai's attempt, Simon stands up in shock and catches Mai with his shadow magic.