Dozuki Aishi was born in 1950 to a pair of extremely wealthy parents. Dozuki's mother worked a highly-demanding job that required her to frequently travel overseas for long periods of time, which caused her to be absent for most of Dozuki's childhood. Dozuki's mother tried to compensate for her lengthy absences by spoiling her daughter as much as possible whenever she had the opportunity; she showered Dozuki with gifts and praise as often as possible, and never said "no" to anything that her daughter requested. As a result, Dozuki developed into a very spoiled young woman who was accustomed to having everything she wanted handed to her on a silver platter without ever working for it.

Like all other members of her bloodline, Dozuki is afflicted with the "Aishi Condition," a disorder which causes her to feel a perpetual sensation of emptiness, as if something crucial is missing from her life. In 1967, while attending high school, Dozuki came into physical contact with a young man whose presence could mysteriously alleviate the symptoms of her condition. Dubbing this young man her "Senpai," Dozuki was determined to turn him into her lifelong companion - however, there were other girls vying for his attention, and Dozuki had no experience with romance. It appeared as though wooing this young man would require hard work, which Dozuki was firmly opposed to.

As usual, Dozuki went crying to her mother and begged her for a solution. By this point in time, Dozuki's mother had retired from her highly-demanding job, and could afford to spend all of her time (and vast fortune) doting on her daughter. She decided that the most efficient way to fulfill Dozuki's needs was to kidnap her Senpai, break his spirit, and turn him into a sort of "pet." To accomplish this, she would need two things: time and privacy. After considering all of her options, she ultimately reached the conclusion that the only way to accomplish her goal in complete secrecy would require an addition to her house: a basement.

In Japan, homes typically do not have basements due to earthquake concerns, flooding risks, and cultural preferences. Dozuki did not wish for local authorities to be aware that she was adding a basement to her home - since it would only be used for illegal purposes and could be a liability for her in the event of a police investigation - and so it was constructed in complete secrecy with the assistance of foreigners who were paid handsomely to stay silent about what they were building. Despite the numerous difficulties in accomplishing this task, the basement was constructed within a year's time. Immediately after its completion, Dozuki's Senpai was kidnapped and imprisoned there.

During the 1800s, one of Dozuki's ancestors discovered a torture technique that could "break" a person mentally. The technique does not involve physical pain; it would be most accurate to describe it as a form of hypnosis. The Aishi hypnotizes the victim into thinking that they are experiencing various types of extreme physical torture; having their fingernails torn out, having every bone in their body broken one by one, having their organs removed from their torso, being lit on fire, being drowned, etc. In reality, absolutely nothing is happening to the victim. However, in the victim's mind, they are undergoing all of the most physically painful experiences imaginable.

Throughout this process, the Aishi is also doing something else - giving the victim hope that they can escape, and then yanking the hope away. The cycle of providing hope and squashing hope gradually conditions the victim to believe that there is no reason to consider resistance or imagine a better future. Once the victim is completely convinced that there is no hope, and that their life is already over, their mind enters a "malleable" state where they can be re-shaped into anything their captor wishes for them to be - even a pet. This is exactly what Dozuki did to her Senpai; she deliberately transformed him into a shell of a man with no will of his own - a "mind-broken slave."

With her mind-broken "husband" at her side, Dozuki's easy life continued as before; she lived as selfishly as possible, relied on her doting mother for all of her needs, and never worked a day in her life. In 1971, she gave birth to her first daughter, Ryoba. Dozuki had absolutely no interest in childrearing, and let her mother and husband raise the child, while doing only the bare minimum amount of work that was required of her. In 1976, she gave birth for the second and last time. Ryoba, who resented her mother for being lazy and selfish, and did not want to see her grandmother's workload increase, took it upon herself to care for her younger sister.

For many years, Dozuki, her mother, her father, her husband, and her two daughters all lived under the same roof. However, once Ryoba found her own "Senpai" and eventually brought him into their home, Dozuki decided that the house had become too crowded, and that it was time for a change. However, instead of simply kicking Ryoba and her soulmate out of the house, Dozuki decided to relocate to Tokyo. She - along with her parents, husband, and daughter - moved out of Buraza Town, leaving Ryoba and her Senpai alone together in their old house. Now residing in Tokyo, Dozuki continues to live comfortably and selfishly, with her elderly mother still taking care of all her needs.