A shopping street bustling with shoppers. Suddenly, a man with a willow-blade knife jumps out and attacks passersby one after another. Hey, stop it!" Masako Murata tries to get out in front of the attacker. Then a shabbily dressed, hooded woman suddenly appears and stands in front of the killer, saying, "If you want to kill, kill me...." The woman tries to mercilessly finish off the attacker, but Masako stops her.
Suddenly, a mysterious woman named Sana with a scar on her back appears before Masako. Sana once made a contract with her employer as a ninja in the Warring States Period, and has lived her life without disobeying his orders. When Masako learns that Sana is a lifelong loner, she decides to keep her at home over the objections of her daughter-in-law, Kyoko. One day, while Masako, Sana, and Matsuda are gathering at Mitsuko's "Tenshukaku" restaurant, Masako's best friend Yayoi comes to them and asks them if they can help her.
Masako and Sana go with Mitsuko and Chiseko to Matsuda's kobudo care class, where they meet Tatsu Yamaki, a delivery man who comes to deliver their box lunches. Chiseko tells Masako that he has a criminal record and is suspected of being the culprit in a series of pickpocketing burglaries that are now taking place in the neighborhood. Even at work, Yamaki is shunned by his peers because of his criminal record. At last, the burglary turns into a murder case. Masako and her friends think that they can't count on the police, so they start their own investigation to protect themselves.
Detective Ichinose is convinced that Sana is a related to the "hooded man" case that has been making headlines recently, and questions her... Yamaki has taken the liberty of setting up a website for trouble-solving. The first request is a mysterious coded e-mail with "Sanya 296" written on it. Yamaki and Mitsuko begin to investigate it. Meanwhile, at the Murata household, the daughter-in-law Kyoko is worried about her daughter Kanako's request for a large allowance. Masako also feels uneasy and decides to let Sana find out. Kanako goes shopping with Sana and finds that she has difficulty making friends because of her limp and has recently made.
Detective Ichinose is asked by Sana to investigate the disappearance of Masako's daughter Yukari 24 years ago, but his boss Shuto interferes. Masako, Yayoi, and Chiseko are selected by lottery to participate in a two-day and one-night trial stay at a nursing home. The three are excited to participate in the program, which includes a full-course French dinner, and the director Sakurai is reputed to be quite handsome. However, Masako is concerned that Yukino, who works at the home, is cold toward the residents, and gives her the business card of the "Tenshukaku" snack bar.
Takeru Ando, a company employee, suddenly arrives at the snack bar "Tenshukaku" and asks for proof that his wife, Kaho, has abandoned their 4-year-old son, neglected housework, and is 3 million yen in debt. Masako and her family are not convinced by Ando's attitude, which they mistakenly believe to be that of a credit agency, but they are worried about the child, so they decide to begin their investigation... As a result of the investigation by Yamaki and Mitsuko, it turns out that Masae Yamada and her friends control the kindergarten that Kaho's son attends, and that they recommended expensive brand-name bags to their mother's friends as being available at a reasonable price, and that Kaho apparently borrowed money to buy those bags. When Masako visits Kaho's house pretending to be a plumber, she finds a dilapidated room and a weary Kaho...
A suspicious letter arrives at Masako's house stating that she knows the truth about her daughter's case.... Sana is worried about Masako, who has been acting strangely since the letter arrived, and Masako slowly begins to tell her about the disappearance of her daughter Yukari 24 years ago. Sana, who knows of Masako's suffering, entrusts the suspicious document to Detective Ichinose and asks him to investigate. Kaori Moriyama runs into the snack bar "Tenshukaku" looking frightened. Kaori married her husband Moriyama, a company owner, six months ago, and they were living happily ever after. However, someone has been trying to kill her for the past month or so, and she asks Masako and the others for help, fearing that she will be killed if her situation continues.
The white bones discovered turn out to be those of a girl who disappeared 24 years ago in a series of disappearances of young girls. Masako is shocked to hear that the bones of her daughter, Yukari, are probably among them, and she becomes depressed. Detective Shuto comes to Masako's house and confesses that the investigation of the 24-year-old case was terminated due to pressure from a certain person, and hands Masako a newspaper clipping and tells her that the person is the culprit. The article mentions former Chief Cabinet Secretary Takizaki and his son, Tetsuhiko Takizaki. Detective Suto also arrives at the "Tenshukaku" snack bar. He is there to unravel the case of Masako's daughter...
