Aquamarine Hoshino

Aqua Hoshino「星ほし野の アクア, Hoshino Akua?」, full name, Aquamarine Hoshino「星ほし野の 愛あ久く愛あ海まりん, Hoshino Akuamarin?」 or more commonly referred to as just Aqua「アクア, Akua?」, is the male protagonist and one of the titular characters of Oshi no Ko. In his previous life, he was known as Gorou Amamiya, a medical doctor who was murdered by a stalker of one of his patients, Ai Hoshino, and reincarnated as the latter's child.

An orphan and a fan of Ai in his previous life, he enjoyed being her child, entering the entertainment world from an early age. Unfortunately, this happy life ended when the same stalker who killed him in his previous life murdered his new mother as he watched. This event fundamentally changed him, prompting him to go down the dark side of the entertainment industry to find the person who sold Ai out, his father.

When his primary suspect turned out to be already deceased, he temporarily gives up on his quest and allows himself to live a normal life. However, his vengeance returns, stronger than ever, once he realizes that he targeted the wrong person, and upon finding his real father, he hatches a plot to expose his crimes.

As a child, Aqua was often called cute by those around him. As he grows older, Aqua becomes a teenage boy of average height who is described as "handsome" with orangish-blonde hair, much like his younger twin sister Ruby Hoshino. He also has long bangs hanging on the left side of his face and aquamarine blue eyes, which his late mother Ai Hoshino named him after, that features a white/light blue star in his right eye, symbolizing that he and his sister are halves of their mother. His star sometimes blackens depending on his mental state and his eyes become darker in color, even gaining an additional black star in his other eye in some chapters. Other times, the stars completely disappear, also depending on his mental state.

He often changes his appearance due to his job as an actor.

At school, Aqua is often seen in his school uniform. The uniform consists of a white collared shirt with light gray slacks, a red necktie hanging down from the collar, and underneath the shirt, he wears a blue blazer with black lapels and gold trimmings, and for footwear, he wears burgundy penny loafers.

During the rehearsal for Tokyo Blade, he wears a cream long sleeved sweater with maroon trimmings as well as a wheat-like print on the left side of the chest, dark gray pants, black ankle socks, and navy and gray sneakers with dark blue laces and dark gray soles.

Due to being Ai's son, many people were able to point out their similarities despite being unaware of his pedigree. Much to Aqua's dismay, as before Chapter 105, he wanted to keep the truth about his late mother from being known to the general public. He also bears a strong resemblance to his biological father Hikaru Kamiki.

Before the tragedy that struck his family, Aqua was considered relatively normal other than his unparalleled prodigious talent in acting even as a child and his quick wit and intelligence like reading complex books. With him retaining his past experiences, he accomplished many things not expected for someone his age. Performing acting jobs was something he was open to and excelled at.

After the tragedy that killed his mother, Ai Hoshino, he changed and became cold, calculated, cunning, and discreet, willing to do whatever means necessary to see his goal of finding his father through. His psychological trauma from Ai's murder tends to resurface anytime he seems to forget his goals. This is the case when Kana Arima suggested that he'd look back at his happy memories in Chapter 50 to improve his acting on the spot. It is a case of Post-Traumatic Stress Disorder and doubles as an active reminder to not stray from his original purpose of vengeance. He blames himself for being weak-willed during that moment, even though he was but a child. However, he used these negative emotions to exemplify his acting performance during his scenes in the Tokyo Blade Theatrical.

Aqua is described as someone with emotional distance; he is shocked when he hears from Kana that he is ''gloomy'', but despite this, he does genuinely care about the people close to him. Aqua is overly protective of Ruby, his younger twin sister. It is mainly described by Taishi Gotanda, his mentor, as someone with a sister complex, which is understandable since he was initially unwilling to let his sister become an idol and suffer the same fate as their mother. Thus, he surreptitiously destroyed almost every chance Ruby could get to be promoted due to this overprotective nature, despite knowing how she longed to follow in their mother's footsteps. Ultimately, he helped Ruby and the new B-Komachi group prepare for a gig so they could accomplish a task long thought impossible. He was also one of the main driving forces behind a project that served to save Akane Kurokawa's reputation.

Arguably, Aqua's greatest talent is his ability to mimic as demonstrated when he puts on a disguise and pretends to be Pieyon.[16] His mimicry is so uncanny that he is able to fool his own sister.

In terms of acting, it is Aqua's nature to reenact samples that he saw somewhere, as noted by Kana.[17] And after watching tapes of his performances when he was younger, Akane Kurokawa concludes that Aqua's acting was all planned ahead of time.[18] Furthermore, Aqua has also demonstrated his ability to improvise on set.[19] Taken together, it suggests Aqua follows the Meisner technique, an acting technique that emphasizes on emotional preparation, repetition exercises, and improvisation.

Due to working for Taishi Gotanda as an intern, Aqua has also become proficient at editing videos. He has also shown proficiency at typing and using a computer.

Other prominent characters:

Akane Kurokawa「黒くろ川かわ 茜あかね, Kurokawa Akane?」 is a major supporting character in Oshi no Ko. She is a top-class method actress affiliated with the Lala Lai Theatrical Company that was introduced as Aqua Hoshino's co-star in the reality dating show LoveforReal.

Ai Hoshino「星ほし野のアイ, Hoshino Ai?」 was the original titular character and the poster child of Oshi no Ko. She was the lead idol of the original B-Komachi and mother of Aqua and Ruby.

As an idol, she lived a life of deceit by pretending to genuinely love her fans. After becoming pregnant with the twins, to not squander her reputation, she gave birth and raised them in secret, playing the role of both idol and mother. However, her lies inevitably caught up with her when she was fatally attacked by a disgruntled fan, using her final moments to tell her children that she loved them.

Ruby Hoshino「星ほし野の瑠る美び衣い, Hoshino Rubii?」, more commonly referred to as just Ruby「ルビー, Rubī?」, is the female protagonist and one of the titular characters of Oshi no Ko. In her previous life, she was known as Sarina Tendouji, a terminally ill patient who was cared for by Gorou Amamiya and, following her death, was reincarnated as the child of her favorite idol, Ai Hoshino.

Kana Arima「有あり馬ま かな, Arima Kana?」 is a major supporting character in Oshi no Ko. She is a childhood acquaintance of Aqua and Ruby Hoshino and a prodigious child actress, though her popularity has waned over the years. She is also the center of the revived idol group B-Komachi.

Mem-Cho「MEMめむちょ, Memu-cho?」, real name unknown, is a major supporting character in Oshi no Ko. She is a popular YouTuber, former TikToker, and a member of the revived B-Komachi.