Oshi no Ko: Who is Aqua and Ruby’s half-brother?

While the identity of Aqua and Ruby’s father still remains a mystery, Oshi no Ko Season 2 has revealed their half-brother.

At first glance, Oshi no Ko seems like a lighthearted drama about the entertainment industry. But the deeper we get into the story, the darker it becomes. The first time we realize this is when we meet Ai Hoshino, a popular teenage idol who’s become pregnant.

Ai never reveals the father of her children, even to her closest people. While it’s a mystery intriguing enough, it becomes even more so when the unknown person orchestrates her murder at the hands of her obsessive fan.

Since the horrifying incident, Ai’s son Aqua has been looking for his biological father to exact vengeance. However, finding the man proves to be incredibly difficult as he knows nothing about him. But in Oshi no Ko Season 2, Aqua finally finds a link to him. (Warning: Spoilers ahead!)

Who is Aqua and Ruby’s half-brother in Oshi no Ko?

Taiki Himekawa is Aqua and Ruby’s half-brother in Oshi no Ko.

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A well-known award-winning actor, he’s introduced in the story during the 2.5D Stage Play Arc. He’s one of the actors in the Lala Lai Company’s Tokyo Blade stage adaptation, cast as the protagonist, while Aqua, Akane, and Kana play Touki, Saya, and Tsurugi, respectively.

As the group prepares for the stage premiere, Aqua realizes that one of his co-stars is his half-sibling, and does DNA tests for each of them. Toward the end of the arc, he learns that Taiki is the half-sibling he’s been looking for, and may know the identity of their shared father.

With that in mind, he reveals the truth to Taiki. The older man, in turn, discloses everything he knows about his parents. His father was Seijuro Uehara, a minor actor, who killed his wife and then himself when Taiki was a kid. 

This information leaves Aqua distraught as the man he’s been looking for all this time is dead, meaning he can’t avenge his mother anymore.

They share a complicated family history

Unknown to both Taiki and Aqua, their real father is not Seijuro. As it’ll be eventually revealed, Lala Lai Company’s president Hikaru Kamiki fathered them both.

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Hikaru was orphaned as a child and led a lonely life until he joined the Lala Lai Company at the age of 10. There he met Airi Himekawa, a well-known actress and Taiki’s mother. But the woman lured him into a physical relationship and eventually conceived Taiki.

She lied to everyone about the child being Seijuro’s, all the while emotionally abusing Hikaru for years. At 15, he met Ai and eventually began dating her. However, she broke up with him before she found out that she was pregnant.

The breakup affected Hikaru’s already damaged psyche a lot, prompting him to reveal the truth of Taiki’s birth to Seijuro. Upon learning the truth, the man killed Airi and then himself. After their death, Taiki was adopted by Toshiro Kindaichi, one of Lala Lai Company’s founding members.

Since Taiki was young when his parents died, he never knew about Seijuro not being his real father. He thought the man was a cheater who got Ai pregnant out of his jealousy of his wife’s talent and success. 

Despite his connection to Aqua and Ruby, Taiki doesn’t play a crucial role in the following arcs. After his stint in the Tokyo Blade, he plays the role of Seijuro in Aqua’s ‘The 15-Year Lie’ movie.

Aqua won’t find the true identity of his biological father until the Mainstay Arc, which won’t be adapted into Oshi no Ko Season 2. But you can always pick up the manga to find out what happens next.

And if you’re looking for some more anime shows, check out our guides to Dandadan, Dragon Ball Daima, Sakamoto Days, and Demon Slayer: Infinity Castle movie trilogy.