|Relationship Status||In a relationship|
Eirin Yagokoro is one of the main antagonists Imperishable Night, the eighth game in the Touhou Project series and continuing to make further appearances throughout the franchise.
Eirin is an enigmatic girl surrounded by many mysteries, giving incoherent replies as answers regarding the mysteries surrounding her. She's a medical genius from the Moon and along with the aid of Kaguya's power to manipulate eternity, was even able to create the Hourai Elixir, which can grant immortality to who drinks it. In addition to her medical knowledge, Eirin seems to be very skilled in various forms of magic. For instance, in Imperishable Night, she sealed the whole Earth preventing anything or anyone from reaching or leaving it. Additionally, she replaced the real Moon with a fake one that was able to mislead the heroines with an illusion.
- Her story: A long time ago, Eirin was the Sage of the Moon; with her high intelligence and the aid of the former Princess of the Moon, Kaguya, she created the Hourai Elixir and gave it to her. As a result, Kaguya was exiled to Earth as a punishment for drinking the elixir. A few years later, Kaguya had been allowed to return to the moon and, along with other Lunarians, Eirin was sent to Earth as an emissary from the Moon. Eirin felt sorry for Kaguya because she herself wasn't punished even though she was the one who made the elixir. Her desire for redemption was so strong that she was ready to do anything for Kaguya, and so she killed all the other emissaries and decided to live on Earth with Kaguya as her own punishment.
- She is living in exile in Gensokyo after choosing to stay with and devote herself to Kaguya Houraisan on Earth rather than take her back to the Moon.
- Blushed just when Kaguya touched her hand.
- Can't stand being separated from Kaguya.
- Dreams about hugging Kaguya.
- Under the moonlight, she hugged Kaguya.
- Gets shy when Kaguya flirts with her.
- Made a promise with Kaguya to live together forever.