Oshi no Ko is a dark, multi-genre anime series that focuses on the deceptively brutal and stressful world of musical idols, first explored through the eyes of Ai Hoshino. Ai was introduced as a conflicted musical idol, a teenage girl who had never known love but had to project a loving image to her countless fans. Then she became a mother, which only deepened her insecurities.
Ai expresses her troubled feelings not just through words, but with her eyes -- which have six-pointed stars on them. These are a visual cue to Ai's true feelings, and notably, her twin son and daughter have one eye star each, which says a lot about this bizarre found family and what they think of each other. Oshi no Ko eyes are always a valuable insight into what each character is thinking and what they're lying about, and that even includes non-family members like Akane Kurokawa.
Why Ai Hoshino Has Two Eye Stars in Oshi no Ko
Ai Hoshino's eye stars are a visual cue for her emotional state. At a glance, they appear to represent her sheer energy as a pop idol and seemingly make her stardom literal. The people who meet her might see it that way, but Ai's eye stars actually represent two darker details.
The first of these is lies, a major theme in Oshi no Ko, since Ai Hoshino lies to all her fans about loving them. Ai must maintain a cheerful facade as the idol industry demands, but it's tough work. Eyes are a window to the soul, as the saying goes, and if she is lying so much, then Ai's eyes are the perfect display of what she's really thinking -- that she's knowingly lying to everyone about love. Ai grew up as miserable orphan who never knew familial or romantic love, and she feared that this made her unsuitable to be an idol. Then, Ichigo Saito encouraged Ai to simply embrace deception and present herself as an idol who truly loves her fans, hence the Oshi no Ko star eyes.
The second reason for Ai Hoshino's eye stars is even more personal -- her motherhood. Ai didn't plan on having kids, so when her twin son and daughter were born, she felt insecure about parenthood. Because Ai had never personally known love, she feared she didn't love her own children, either. She worried that she was lying to herself about being a proper parent, to the point she never told Aquamarine and Ruby "I love you" since she feared it wouldn't be true. When she got stabbed and bled to death, however, Ai realized she truly did love her children and admitted it to herself, allowing her to die happy.
Why Aqua & Ruby Hoshino Have One Eye Star Each
Genetics might explain why Aqua and Ruby have one eye star. Their mother had two and their unknown father probably had none, so Aqua and Ruby would end up with split genes. Most likely, though, Oshi no Ko gave them their own eye star to show they have some thematic overlap with their idol mother -- but with key differences. They may be Ai's biological partial-isekai children, but on the inside, Aqua and Ruby are both very different from her.
Aqua and Ruby each started with an incomplete set of Oshi no Ko star eyes because they share just one trait with their mother -- living a life of lies. They accidentally lied to Ai about being her true children, since they are different people on the inside with much more than an infant's mind. Aqua is the reborn Dr. Gorou, a grown man, while Ruby is Sarina Tendouji, a middle school-aged girl who passed away in Dr. Garou's rural hospital before realizing her own distrant dream of being an idol. They maintained this facade to their mother and the entire world, outwardly going by their new identities of Aqua and Ruby while openly being themselves with each other. Whether these kids get involved in the idol industry or not, they are already used to lies and have an eye star to show for it.
Aqua and Ruby lack a second eye star because they are not insecure about love like Ai was. While Ai feared she didn't truly love her children, they were fully confident in their adoration and support for their mother, and to them, loving their idol was a sacred truth. Ironically enough, this pure and honest love may make them both more miserable, with Aqua potentially ruining himself to seek revenge on Ai's killer while Ruby dives into the same brutal idol industry that once sunk its claws into her mother.
Oshi no Ko Eyes Meaning in Other Characters
For the first few Oshi no Ko episodes, only the three Hoshinos had these distinctive star eyes, but then the narrative expanded upon the meaning of those eyes with non-family characters. In rare, emotionally-charged cases, other characters can obtain star eyes, as the dandere actress Akane Kurokawa did partway through Season 1. After her trauma with ego-surfing and cyberbullying, Akane was grateful for Aqua's help and vowed to become his dream girl, to the point she almost became a yandere.
Akane forced herself to become someone she is not -- Ai Hoshino -- and she embodied that lie with all her might. That meant Akane had star eyes when she saw Aqua again, blending her own identity with Ai's and lying to everyone about her true nature. It remains to be seen for how much longer Akane will rely on this obvious falsehood as her love triangle with Aqua and Kana continues. Either Akane will have the courage and confidence to continue that triangle as herself, or she won't, and it will say a lot about her character either way.
By contrast, Kana Arima has no eye stars, even though she also suffered in the entertainment industry as a washed-up child actor whom everyone abandoned. Like Ai Hoshino before her, Kana feared that there was no love and acceptance in her life, but unlike the Hoshinos and Akane, Kana never tried to become someone she is not to fix these problems. The proud tsundere Kana Arima is determined to succeed or fail as her true self, and she actually forces other characters, like Ruby and Akane, to change themselves to suit her instead.
Despite Kana's own drama and stress, she has a solid and honest personal foundation to stand on, being true to herself and to others. This lack of lies and eye stars may be why Kana is Oshi no Ko's most popular character. Akane and the Hoshinos think they can get ahead with deception and fooling themselves, but Kana proves that even in this thematic anime about lies, the truth is always strongest, and she has clear, focused eyes to prove it.