(and, actually, book 10 started; I just didn’t have time to write anything about it earlier)
Chapter 4 was a day in the life of one of Antonia’s trainee maids, who happens to also be one of her classmates at school, and the younger sister of one of Kio’s film-club seniors. Yuki Nishihara appeared very briefly in book 8, as one of the many girls who’d come to look up to Maya. When offered the chance, she decides to emulate her idol, and after a rough start, finds that she rather enjoys a life of service, even if she still can’t shoot a Glock very well. Privately, Maya has high hopes for Yuki; Antonia initially doubts, but after making a point of spending time with her, starts to shares Maya’s opinion. Aoi shows up briefly toward the end, still panicky and flustered when someone mentions her obvious feelings toward Kio.
Next comes the final intermission with Ichika, cleaning house after the New Years party with her parallel selves. As she takes out the trash, she notices something unusual: an assistoroid out on his own, running along the fence to some unknown destination. It is, of course, 6-chan, and, curious, she follows him.
Chapter 5 starts by flashing back to a day when 6-chan was out playing soccer with some neighborhood kids, and a particularly strong kick knocked him over and sent the ball into the yard of a supposedly-unoccupied house. He hops over the fence to retrieve it, and sees signs of fresh occupancy, but no ball. Activating his sensors, he detects the footprints of a small dog dragging the ball inside, but there’s no sign of the owners. Cautiously, politely hovering above the floor (no shoes to take off!) and holding up a signboard apologizing for his intrusion, he enters.
Following the dog’s tracks, he passes a large number of moving boxes, but is surprised when the dog runs out of a room and knocks him over. It can’t hurt him, but his programming prevents him from doing anything violent to break off the (trivial) attack, and he’s outmassed. A young girl hears the commotion, and calls off the dog, politely apologizing to her unknown visitor. He holds up his signboard to communicate with her, and then realizes she’s blind. At the same time, she realizes he must be mute. Her name is Mahiro, and she’s around 12.
When she returns the ball, he carefully spells out a thank-you on the palm of her hand, and they chat a bit before he leaves. Soon he’s visiting Mahiro every day at the same time, bringing snacks and little presents, and telling her stories about the places he’s gone and the things he’s seen. They become good friends, and he learns how she started having headaches two years earlier, and eventually lost her sight due to a tumor pressing on the optic nerve, and how her father gave up his career in Tokyo so she could be treated by a noted specialist in Okinawa. Her parents are happy that she’s become more cheerful, but worried that her unseen “friend” may be a hallucination.
Eventually, Kio notices 6-chan’s frequent absences, and asks the other assistoroids. They inform him that they don’t know where he goes, and, unusually, he hasn’t done any data-sharing about it. Kio thinks of assistoroids as people, and it never occurs to him to order a direct investigation of 6-chan’s memories; he simply asks Sada-yan to look into it and tell him if there’s a problem.
The next time 6-chan sneaks out, Sada-yan follows him, and confronts him outside Mahiro’s window. 6-chan shares everything, and Sada-yan asks to be introduced to her. In fact, his eagerness to meet her is almost matched by his eagerness to share the snacks his sensors detect in her room: dango, his favorite food.
After a long, pleasant visit, the two assistoroids leave through the window and hop over the fence, and are shocked when a voice calls out to them, and Ichika appears out of thin air. She starts to tease them wickedly about their secret outing, when she’s interrupted by a scream from inside the house. Mahiro’s mother has found her daughter collapsed on the floor. Unknown to everyone, there was another tumor, and she’s rushed to the hospital.
6-chan and Sada-yan use their emergency teleport to return home, and while Sada-yan explains to Kio, 6-chan rushes to find Eris’ handheld healing device and begs her to use it to save their friend. Cut to the doctor explaining to her parents that there’s nothing they can do for Mahiro.
Eris can’t help. With the diplomatic situation still up in the air, interstellar law prevents her from using level 3 medical technology on a human who’s not directly attached to the embassy. They could try to appeal to Captain Kuune, but it’s not a Catian law; it’s a rule laid down by the Orsonians, similar to the one about not pretending to be gods to primitives. Level 2 med-tech wouldn’t be a problem, but while that could deal with most physical injuries, it’s insufficient for brain tumors. Kio joins the attempt to persuade her, but it’s no good; she is forbidden to work miracles on Earth.
Once again, Ichika appears out of nowhere, and suggests an alternative. In the middle of the night, they sneak invisibly into Mahiro’s room. Ichika uses magic to extract the tumors, leaving Eris a repair job that can be accomplished with only level 2 med-tech. They sneak back out, and leave the doctors to discover the miraculous remission.
It’s a brief local sensation, but no one can explain what happened, and only the tabloids really pick it up. Antonia, who carefully reads every news source, immediately figures out the truth and shakes her head at the stupid chance Eris and company have taken. After a few weeks of careful tests, the puzzled doctors release the fully-healed Mahiro, and Kuune announces that the authorities on Catia have, despite some major commotion, decided to let this one go without punishment, but it can never happen again. With the case closed, 6-chan and Sada-yan are free to visit her again.
They rush to her house, but find it empty, with just a note taped to Mahiro’s window. With her cured, her father is free to resume his career, and the family is returning to Tokyo that very day. Sada-yan pulls out his custom-built motorized tricycle (have I mentioned that before? hmmm, perhaps not; anyway, he stores it in hammerspace), and they rush to the airport, parking it right in front of the doors and running to the gate.
In the airport, Mahiro is both happy and sad. She can see again, she’s going home to all her family and friends, but she’s starting to share her parents’ doubts. Were her little friends just a hallucination after all? She closes her eyes to rest a bit before the flight, and is annoyed to hear a commotion. People are making a fuss like they’ve spotted celebrities, shouting things like “kawaiiiii”, “hey, look, assistoroids”, “camera! where’s my camera?”.
She’s surprised when the commotion comes right to her, and she looks up to see two completely unfamiliar cat-robots. 6-chan quietly takes her hand and spells out a question, asking if she’s really leaving. At the familiar touch, she instantly recognizes her friends, and embraces them both, crying happily. She looks up and tells her parents that these are the precious friends she made in Okinawa.
Later, they return home and explain everything to Kio. He nods and starts to head off for dinner, but they stop him and ask him to step outside for a moment. When he opens the door, he finds Sada-yan’s trike parked outside, ticketed and towed for being left in a no-parking zone at the airport.