For the history of Majima Goro prior to his death, see Original Majima
Sato Atsuko was born in a small village in rural Kansai. She moved to Osaka alone to attend high school, as her village had no high school and she had always dreamed of living in a big city. However, she struggled both academically and financially. She was naturally impulsive, and had a chip on her shoulder about her humble origins, leading to massive overspending in a desire to keep up with the more popular and wealthy girls she knew.
This overspending eventually lead to her getting into debt with the Yakuza, and when she couldn't pay up, she was forced to work in one of their clubs as a stripper to pay the debt. Although she didn't initially mind the work, no matter how much she paid, her debt never seemed to go down, and she was eventually pressured into full-service sex work which she hated.
Desperate to escape the life, she began hunting for a man to marry, but her husband quickly revealed himself to be emotionally and financially abusive, as well as a serial cheater, and she resolved to divorce him. However, when she told him she was leaving, he attacked her, and she was forced to kill him out of self-defence, stabbing him with a pair of kitchen scissors.
When her murder was not discovered, as his death was blamed on the local Yakuza with whom he had some shady dealings, she became a black widow, marrying men for their money and then quietly killing them, usually by poison. Although some of the men were comfortably off, she had never fully grown out of her impulsive spending and extravagent tastes, and she quickly burned through the money, requiring her to repeat the process.
By the time she was murdered by
Nishitani Homare, as a 'gift' to Majima Goro, she had killed five men.
As he was killing her, she asked Nishitani why he was doing this to a stranger, and he openly told her it was for Majima, so when her spirit rose from the grave as an Onryo, a vengeful ghost, it was Majima rather than Nishitani she sought revenge against.
She tracked him to Tokyo, in time to see his death during the climax of the empty lot business at the hands of
Shimano Futoshi. Deprived of any other way of wreaking her vengeance, she chose to possess his corpse to allow her a temporary return to the pleasures of the living.
However, for unknown reasons, on possessing Majima's corpse, she gained his memories, including his emotions.
She went to ground for several weeks, while the two consciousnesses wrestled for control, but the being that eventually emerged was gestalt, having both sets of memories and elements from both original personalities.
They returned to Shimano's service, Majima's bond with him too strong to break, at least with Saejima still in prison, although the Onryo made no secret of her dislike for him, resulting in a strangely antagonistic relationship despite their ultimate loyalty.
Majima's passion and fighting skills, combined with Atsuko's rage and experience as a cold-blooded killer, made a lethal combination, and the new Majima became Shimano's attack dog and, when needed, assassin, quickly rising through the ranks to become Captain of the Shimano family, and even Patriarch of their own family.