Aqua Hoshino

"The guy who made Ai go through such a thing is in the entertainment world. Since that guy is related to me by blood, I can track him through genetic testing with a piece of hair. I can't die yet. Not until I find him. and kill him with my very own hands."

Aquamarine Hoshino (星野・アクアマリン) is the titular main protagonist of the series. He was known as Gorou in his past life, a medical doctor who treated patients. He developed an obsession for idols (specifically for Ai Hoshino, an idol of the defunct idol group, B-Komachi) after encountering Sarina, one of his patients who held that same infatuation. He was reincarnated along with his twin-sister Ruby Hoshino, formerly known as Sarina, and is now the child of Ai Hoshino.

In his new life, after the death of his mother, he swore he'd do anything to find whoever was behind it; unrelenting in his goal, unlike his sister. Many of his actions are driven by this very ambition. He is willing to do anything to get closer to the truth.

Appearance
Aqua is a blonde and is quite tall. He has blue Aquamarine eyes, which is what his mother named him after. He often changes his appearance due to his job as an actor. He is described as "handsome" and features a star in his right eye; symboling that he and is sister are one half of their mother.

Due to him being Ai Hoshino's son, people point out their similarities, much to Aqua's dismay; wanting to keep things secretive about their relationship.

Personality
Before the death of Ai Hoshino, Aqua was relatively normal, however, him having the experiences of his past life, he was able to do things unexpected of his age. Performing acting jobs was something he was open to and excelled at.

After his mother's death, however, he was a changed man. He became cold, calculated, cunning, and discreet. He transformed into a man willing to do anything to see his goals through.

Despite this, he does genuinely care about the people around him. He's unwilling to let his sister become an idol because he doesn't want her to end up like their mom. He helped the new B-Komachi group in preparing for a gig so they could accomplish a task long thought impossible. He was even one of the main driving forces behind a project that served to save Akane Kurokawa's reputation.

Story
Gorou was a 30 year old doctor and a huge fan of the idol Ai. He was his fan because of a 12 year old patient of his named Sarina used to adore her, before she eventually died. When Ai was pregnant, she came to Gorou's hospital to give birth to twins. Because he was in charge of her, he was murdered by an anonymous stalker and was reincarnated into Hoshino Aquamarine, the son of Ai.

At the age of 4, Aqua witnesses his mother getting stabbed by that same stalker after answering the door, who later committed suicide. However, Aquamarine thinks it's more than a simple "crazed stalker" situation and believes the stalker had been given information about her location by someone close to Ai, which he theorizes is their unknown father, and swears to avenge his mother's death by killing him.

Trivia

 * Everyone calls him "Aqua" because "Aquamarine" is too long.
 * His mother has one star in each eye, he inherited a star in his right eye and his sister inherited in her left eye.
 * He says he can't really use technology like the youngsters do.
 * He is constantly called a siscon.