Chapter eight of Ma no Kakera. Unlike the other stories in the volume, this one was initially published in Shinkan (シンカン)
Mayumi, the daughter of a wealthy family, suffers from a mental illness whereby she must be given specific instructions at all times as to what to do or say; otherwise, she will be crippled by indecision and unable to do anything for herself. If she is not given instructions, she will constantly ask what she should do. Her father has hired several maids to look after her but they always resign, as they cannot deal with Mayumi's incessant questioning. He advertises for a new carer for Mayumi, and a woman named Mitsu Uchida responds. Mayumi's father explains her condition, which began after the death of Mayumi's mother when she was a young child. Mayumi cries out and Mitsu goes to her aid. She proves to be very patient with Mayumi and enthusiastic about the job. Mayumi's condition begins to show signs of improving, and her father becomes cautiously optimistic.
Mitsu lasts at the job much longer than anyone else. She and Mayumi are inseparable and remain together all day, communicating in their own secret language of whispers and hand signals. However, Mitsu's health begins to suffer and she becomes very ill. Mitsu's father tries to tell her to take a day off but Mitsu refuses; she loves working with Mayumi because it allows her to live again as her "past self." Mayumi's father wonders about this and also notices that Mitsu's face is bruised. Mitsu denies this.
Mayumi continues to improve. Her father begins to believe that Mitsu is a guardian angel to her; not only is Mayumi beginning to recover, but Mitsu's guidance saved Mayumi from walking down a road where there was a fatal accident just moments later. Mayumi's father has an employee run a background check on Mitsu, which reveals that Mitsu lives with a violent, abusive boyfriend named Aga. Mayumi's father worries that Aga may target Mayumi, and begins plotting to separate Mitsu from Aga. Meanwhile, Mayumi is beginning to become concerned about her recovery and what it will mean for Mitsu's job. Mitsu whispers another instruction to her.
Two weeks later, Mitsu is found violently murdered. Aga is the only suspect. Mayumi's father rushes to find his daughter, but Mayumi seems to believe that Mitsu is still with her. She continues to take instructions from "Mitsu", and sometimes Mitsu's whispering can be heard very quietly. Mayumi's father believes that Mitsu is appearing in spirit to guide his daughter. He still wonders what Mitsu meant by wanting to return to her "past self" through Mayumi. Outside, he finds Mayumi stabbing the ground with a knife, asking "Mitsu" if she is doing it right.
A few days later, Mayumi comes home soaked in blood and holding a knife. She tells her horrified father that the blood is Aga's and that she killed him like Mitsu taught her. Mitsu's whispering is heard on the air again.