Satou was born in Hokkaido, where he grew up with relatively normal circumstances. He attended Heisei Bunka University, a private institution, but dropped out after experiencing intense social anxiety and paranoia, which ultimately led to his complete withdrawal from society.

Since dropping out, Satou has lived in a constant state of isolation, trapped in a cycle of self-loathing, procrastination, and escapism. His only financial support comes from his parents, who continue to send him a monthly allowance, allowing him to sustain his parasitic hikikomori lifestyle.

Throughout the story, Satou is forced to confront his fears and delusions, often pushed into situations where he must interact with the outside world—whether through the mysterious Misaki Nakahara, his old high school friend Kaoru Yamazaki, or the various odd jobs and schemes he gets involved in.

Satou has a disheveled and unkempt appearance, reflecting his lack of self-care and motivation. He has messy black hair, tired eyes, and a thin build, often appearing unkempt and sluggish.

He usually wears casual, worn-out clothing, such as a simple T-shirt, sweatpants, or a loose button-up shirt, rarely making an effort to dress neatly. His posture is often slouched, emphasizing his lack of confidence and motivation.

Over time, as he gradually attempts to reintegrate into society, his appearance improves slightly, but he still retains his awkward and hesitant demeanor.

Satou is highly insecure, socially anxious, and prone to paranoia, often fabricating delusions and conspiracy theories to justify his hikikomori state. He believes that an organization called the NHK (Nihon Hikikomori Kyōkai) is behind his withdrawal, making him a victim of a larger conspiracy.

However, beneath his pathetic and cynical exterior, Satou possesses moments of genuine kindness, determination, and even humor. He desperately wants to change, but his fears, laziness, and reliance on escapism constantly hold him back.

His character arc revolves around his attempts to overcome his hikikomori lifestyle, facing numerous failures and setbacks but ultimately growing in small, realistic ways.

• The Birth of a Hikikomori
  Satou’s descent into isolation and paranoia begins when he drops out of university, unable to cope with social pressures and anxiety. As he shuts himself off from society, he constructs a conspiracy theory, believing that the NHK (Nihon Hikikomori Kyōkai) is secretly manipulating people into becoming shut-ins. This delusion justifies his lifestyle, preventing him from taking responsibility for his own actions. Satou’s days are spent lazing around, indulging in online games, anime, and eroge (erotic visual novels), while his apartment falls into filth and disrepair. He remains in complete denial of his situation, convinced that he is a victim rather than the cause of his suffering.

• Manipulation and Codependency with Misaki
  Satou’s routine is disrupted when he meets Misaki Nakahara, a mysterious girl who claims to have a special program designed to “cure” his hikikomori condition. Though skeptical, Satou reluctantly agrees to participate, leading to a series of bizarre and eye-opening experiences. Misaki plays a strange and unpredictable role in Satou’s life. She initially appears as a kind and patient savior, offering him a way out of his hikikomori state. However, as their relationship develops, it becomes clear that Misaki has her own insecurities and is using Satou to feel needed and in control.