Tsukuyomi

"God surely is kind, isn't he? He brought two people who never had a mother in the real sense... and a mother who gave birth to soulless children... together. Perhaps... there's more to that than meets the eye."

The Crow Girl is an unnamed, yet pivotal character in the Oshi no Ko manga series. She is a seemingly supernatural being apparently aware of everything that transpires within the story.

Personality
Seemingly omniscient, The Crow Girl is an enigmatic being whose motives and goals are shrouded in mystery. Befitting her appearance, she bears the overall demeanor of a creepy child, acting mischievous and being unfazed by threats whilst almost always having a smile on her face.

When interacting with people, she tends to tease them about their insecurities. While partly a tactic to quickly get their attention, the Crow Girl seems to be genuinely interested in others' thought processes, implying that she cannot directly read minds. However, should they ignore her, she will quickly change the topic to get their attention back, such as by confronting them about their desires and offering vital information to help them achieve their goals whilst teasingly keeping critical details to herself. Still, she does not appear to be malicious, merely giving her information and inquiring others to think on it.

Background
At some point following Ai Hoshino's death, the Crow Girl confronted Aqua. As he was holding out hope that she might perhaps have been reincarnated like himself and Ruby, she informed him that his mother's soul had left this world.

Private
The Crow Girl is first seen after Aqua tells Gorou Amamiya's backstory to Akane. Having seemingly overheard the conversation despite not even being in the same area, she mumbles to herself how "god must be kind to have brought him, Ruby, and Ai Hoshino together", though she also notes that there "might be more to it".

Later, a crow steals Ruby's keys, prompting the latter to give chase with Akane intow. Upon catching up to the animal at a cave hidden behind a shrine, however, the two girls also stumble across Gorou Amamiya's corpse, who Ruby immediate recognizes from Sarina Tendouji's Ai Fan Club membership card on the body. The strange circumstances that led to the corpse's discovery seem to imply that the crow was, in fact, send by the Crow Girl.

While Ruby was still processing Gorou's death, the Crow Girl confronted her in person. To gain her attention, she initially teased her about her taking Sarina's membership card off the corpse, which she somehow knew about despite not having been there. However, Ruby just angrily brushed her off, forcing her to change tactics.

Movie
Around the same time the movie 15 Year Lie is green lit, the Crow Girl comes to see Aqua, asking him what he is thinking about, his sister, his ex, someone who loves him or even his mother. She repeats the fact that Ai was not reincarnated like he and his sister were and that he should be thinking about why he was reborn at all.

Trivia

 * A popular fan theory is that the Crow Girl is either the deity Yatagarasu or Ame-no-Uzume-no-Mikoto from Japan's Shinto religion.
 * Yatagarasu is also known as the "eight-layered crow", like how the Crow Girl is constantly accompanied by up to eight crows.
 * Yatagarasu is often serves as a divine guide to humans, like how the Crow Girl seemingly guides Ruby and Aqua.
 * Ame-no-Uzume is the goddess of arts, which fits with the themes of Oshi no Ko.
 * Ame-no-Uzume was mentioned Chapter 74, with Aqua commenting that same chapter that he "knows her well".
 * The Crow Girl's statement that Ai's children were "soulless" implies that she would have had a stillbirth if Gorou and Sarina were not reincarnated as her twin children.