A Brilliant Title Recovery
First of all, let me give you a synopsis of the early part of the story.
Goro, a local obstetrician/gynecologist, is a big fan of Ai Hoshino, the absolute center of the idol group “B-Komachi. He is such a hardcore otaku that he plays live DVDs in his patients’ hospital rooms (because, according to him, “seeing beautiful things is good for your health”), and he spends his days in a full life.
Then one day, he received a shock during a medical examination. Ai, who was supposed to be “recovering from an illness,” appears in front of him as a pregnant woman with twins. At first, he is shocked and conflicted, but Ai’s determination to “be happy both as a mother and as an idol” and her resolve to “never disclose the child = continue to lie to her fans with love” make him vow to support her with all his might.

The progress is good, and the due date finally arrives, but then an incident occurs. A “hooded figure” who knows about Ai’s top-secret pregnancy is suddenly attacked on a nighttime street, and she falls off a cliff. In a daze of consciousness, Goro closes his eyelids, wishing Ai a successful delivery. ……
–The next moment he wakes up from the darkness. The landscape of the hospital room unfolds before her eyes. All over her body she feels the warmth of her mother, who is holding her in her arms.
Goro had been born as Ai’s child.
The title “Mystery Child” does not only mean “a story about your favorite child (idol). It also means “a story about a reincarnation of my idol.
The Other Reincarnation
Goro is now living as Ai’s son, Hoshino Aiku Aikai (a.k.a. Aquamarine, a.k.a. Aqua). Confused by the fact of his reincarnation, he gradually begins to adjust to a life in which he can watch his son grow up close to him and receive his love, and decides to support her life in a new way as her son.
There is another who also enjoys the baby life of her guess. Aqua’s twin sister, Rumie Hoshino (Ruby). She, too, is a reincarnated person, and her true identity is Sarina, a girl who was an inpatient at the hospital where Goro worked.
Sarina suffered from an incurable disease and was unable to go to school or exercise, living a near bedridden life. The main source of emotional support for her was Ai, and it was her enthusiasm for Ai that led Goro into the “swamp” of Ai. The two were close friends and engaged in eye talk, but Sarina passed away before Goro at the age of only 12.
Although they knew each other from a previous life, they avoided prying into each other’s past, so even though they knew they were both reincarnations of the same person, they were unaware of each other’s true identity. As “ardent Ai fans,” they work together to support her and cheer her on (even though they are limited in what they can do because she is a baby).
Ai resumes her career as an entertainer while hiding the fact that she has a child. Ai pours out her love to her children and, in turn, they love her back, which helps her to refine her expression, and she finally achieves a remarkable breakthrough that makes her worthy of being called a top idol.
The End and the Beginning
The children were growing up quickly, and B-Komachi was scheduled to perform in a dome. Just when everything seems like smooth sailing, tragedy strikes. Ai was stabbed by a stalker who was upset that she had a child, and died at the young age of 20.
While their fans are heartbroken and the public shows sympathy for Ai, the two are also struck by the malicious words of her stalker and despair. Still, Ruby is determined to become an idol like her mother, with the sparkle of her mother’s light and the love she left behind in her heart.
Meanwhile, Aqua is troubled by the thought that there is an informant, and that this informant may be the same person who killed her (Goro). The stalker who killed Ai is just a student.
The stalker who killed Ai was just a student. Such a person would not be able to find out the address of a celebrity or the secret that has been kept from him. Born into a complicated family and having lived in an institution since childhood, Ai’s father is the only one in the entertainment industry who can know everything about Ai, as he had no contact with his relatives or school. Aqua vows to take revenge by identifying her father through genetic testing.
Thus, the twin high school students, illegitimate siblings of the legendary idol “Ai,” plunge into the world of show business, where emotions swirl around them, with the younger sister as an idol and the older brother as an actor, each with his own thoughts and feelings.