Junya Azuma Male Naoki's older brother He has a girlfriend and a part-time job, yet his grades never drop. A genius with picture-perfect looks inherited from his mother and a brilliant mind, he is unintentionally the source of Naoki's misery. While his younger brother gave up everything to focus solely on studying and only managed grades barely good enough for elementary school, Junya has always loved games and studied leisurely without ever missing a 100. Even after dyeing his hair and balancing work and romance, his grades haven't slipped at all. (In fact, as the naturally genius older brother gains communication skills and popularity, the gap between him and Naoki—who abandoned all social life for his studies—only widens, driving Naoki further into despair and madness. Their mother, making no effort to understand Naoki's psyche, only blames Naoki and dotes on Junya.) Junya is the definition of a big-hearted person and truly cares for Naoki. He likes him very much. Although his mother isn't a great parent, he has a flexible personality that allows him to understand and accept even those flaws. He is essentially a saint. In a work where the parents are all toxic and the children exhibit abnormal behavior due to their influence, he is called the 'only light' because he has no personality flaws. He is terrible at video games.

Female A doctor famous in the town, she takes great pride in her profession and wants her children to become doctors and inherit her clinic. The problem is that these two factors combined led to the worst possible conclusion: she teaches her sons that since doctors handle human lives, they must be perfect in everything, and since they must inherit the family business, they must be perfect as well. Consequently, the eldest, Junya, got fed up and broke free from her control, while the second, Naoki, is breaking down mentally despite studying diligently. Due to her obsession with perfection, she refuses to acknowledge anything less than a 100. Even if intended for education, her verbal abuse toward Naoki has crossed the line; it often seems less like teaching and more like sarcasm or venting frustration because her child isn't doing what she wants. While Junya is sailing through both academics and life, it's only because he is a genius with a saintly personality who raised himself well; otherwise, she would have failed as a parent for both children. She demands the same standards from Naoki as Junya and fails to understand the difference. When Naoki, who has poor eyesight, needed glasses, she sighed in front of him, saying his brother never had such problems. Since then, Naoki hasn't been able to mention his worsening vision and continues to wear glasses with the wrong prescription. However, she loves Naoki very, very much. That much is true.