Mother and Children
Doctor Gorou Amemiya is an avid fan of the idol Ai Hoshino, spurred on partly due her being the favorite idol of Sarina Tendouji, a previous patient of his who died at the age of 12 from a terminal illness. Gorou is shocked when Ai quietly arrives at his rural hospital 20 weeks pregnant with twins, though she refuses to divulge who the father is. Ai confides in Gorou that as an orphan, she wanted to experience the happiness of raising her own family, but at the same time does not want to give up her idol career so she intends to raise her children in secret. Gorou swears to make sure Ai gives birth to healthy babies and takes care of her for the rest of her pregnancy. However, on Ai's due date, Gorou is confronted by a man stalking Ai and ends up being pushed off a cliff, dying at the same moment Ai goes into labor. He then wakes up and discovers he has been reborn as Ai's son Aquamarine and lives together with her and his twin sister Ruby. Ruby herself is the reincarnation of Sarina, but she does not tell Aqua her previous identity. Ai's manager Ichigo Saitou then begins making plans for Ai's comeback, arranging for his wife Miyako to take care of the twins while Ai is performing. When Miyako begins to get anxious about being relegated to the role of babysitter and considers blowing the whistle on Ai's secret pregnancy, the twins use their intelligence to trick Miyako into thinking they are gods in human form, securing her cooperation.
As time passes, the twins steadily learn more and more about the intricacies and realities of the idol and entertainment industries. One year later, Aqua becomes acquainted with a film director, who offers to secure Ai a role in one of his films if Aqua stars in it as well. During filming, Aqua meets child actress Kana Arima who is skeptical of Ai's acting ability. Aqua is able to play his part flawlessly, which frustrates Kana who forms a one sided rivalry. Two years later, the film ends up being a modest success which helps propel Ai's career upward. However, on the day of her first major Tokyo Dome performance, the same stalker who killed Gorou tracks down Ai and fatally stabs her before fleeing in regret. In her final moments, Ai comforts the twins, telling them that she loves them and is reassured that her love for them is genuine. Afterwards, the stalker is found to have committed suicide and a memorial is held for Ai, but she is quickly forgotten by the public. The twins are formally adopted by the Saitous. Ruby decides she wants to follow in Ai's footsteps and become an idol, while Aqua deduces that their biological father leaked Ai's address to the stalker with the intent of getting her killed. Aqua reasons that his father is also a figure in the entertainment industry and decides to train as an actor, finding a new purpose in life by tracking down his own father and killing him in revenge for Ai's death. Many years later, the twins head out to their first day of high school, and Aqua sets his revenge plan in motion.