The narrative follows Sato Yu, a high school student who works a part-time job for an evil organization. His role is to act as a distraction, shouting and charging at magical girls while his more powerful seniors engage in combat. Yu is a seemingly ordinary student, but his experiences have made him cynical and resigned to his lot.
Chapter 3 begins with Yu on a mission, lamenting the simplicity of his job. His senior, Darumajiron, a massive individual, prepares to undergo a power-up. However, before Darumajiron can fully transform, a magical girl, Sakura Gawa Aika, swiftly defeats him with a single, precise attack, leaving Yu distraught and vowing revenge for his fallen senior.
The following chapters reveal that Darumajiron's funeral has already taken place, a somber event for monsters who disintegrate upon death. Yu mourns his senior, whom he secretly admired as an older brother figure. The narrative takes a sharp turn in Chapter 6 when Aika transfers into Yu's class. To Yu's shock, Aika, who had previously appeared as a pink-haired magical girl with a larger physique, now has black hair and a slender build, and she claims to have come to fulfill a childhood marriage promise with Yu. This revelation leaves Yu bewildered, questioning the nature of magical girls and his own life.
The story then shifts to Yu's part-time job again, introducing Dabujiza, a senior who has fused with a crayfish. Yu and his fellow part-timers are tasked with supporting Dabujiza against the "Seifuku Sentai" (Uniform Task Force), a group of magical warriors in colorful uniforms. The Sentai, numbering fifteen members, engage in elaborate introductions before combat. Yu, despite his low-level role, expresses concern for his fellow part-timers and the overwhelming power of the Sentai, who show no mercy. Dabujiza is eventually defeated, growing to an enormous size before the Sentai deploy a robot.
Yu, having escaped the battle, meets Aika for a date. He treats her to food, and during their outing, Aika expresses interest in sword fighting, recalling Yu's past prowess. Yu, however, is disillusioned with sword fighting after a devastating loss in a tournament, where he realized the vast gap between his abilities and those of powerful beings like magical girls and "Seigi-man" (Justice Men). He feels his childhood dreams were unrealistic.
The next day, Aika invites Yu to watch a "Blade Ruld" (sword fighting) practice. Yu explains the sport's rules, but his past trauma resurfaces, leading him to lash out at Aika when she suggests he participate. He retreats to a park, contemplating his weakness and the inherent power disparity between ordinary humans and those born with special abilities. He reflects on the nature of monsters and magical girls, noting that monsters can be harmless, and magical girls gain power from emotions like love, with their attractiveness correlating to their strength.
The narrative escalates when a powerful, unaffiliated rabbit monster attacks the city. Yu, witnessing the destruction and the potential for civilian casualties, is enraged by the monster's recklessness. Aika arrives, transforming into a pink-haired magical girl and confronting the monster. The monster, sensing Aika's connection to Yu, captures him. Aika, despite her immense power, is overwhelmed and severely injured. Yu, witnessing Aika's plight, is forced to make a difficult choice. He reveals himself as a member of the evil organization, feigning betrayal to manipulate the monster and save Aika. He then absorbs a potent source of evil power, transforming into a more powerful entity.
Yu defeats the rabbit monster, but his actions shatter Aika's heart and her belief in him. She reveals her true form as a black-haired girl who used her magical girl powers to conceal her insecurities. Her powers, fueled by love, are now gone, leaving her unable to feel anything for Yu. She spares him, warning him that their "lover's game" is over.
Yu then seeks out Dr. Ruiko, a doctor at the evil organization's hospital, to find a way to convert evil power into justice power, intending to return the stolen power to Aika. Dr. Ruiko agrees to help, and Yu, now a monster himself, reflects on his actions and the complex nature of good and evil. He encounters his junior, Okamura, who possesses the ability to predict outcomes. They commiserate over their respective failures, particularly Aika's rejection, and prepare for another mission. The story concludes with Yu and Okamura heading to a ramen shop, a small comfort after their recent ordeals.
