Eirin Yagokoro

Eirin Yagokoro is a Lunarian from Touhou Project, first appearing as one of two possible final bosses in Imperishable Night.

An immortal from the moon, Eirin is the creator of the Hourai Elixir as well as the co-founder of the Lunar Capital along with her relative Lord Tsukuyomi. After her friend and mistress Kaguya Houraisan consumed the Hourai Elixir and was banished to Earth, Eirin could not help but feel responsible for Kaguya's predicament, so she betrayed the Lunar emissaries and fled to Earth as a self-imposed exile, living with Kaguya. During the events of Imperishable Night, Eirin seals the Earth inside a chamber to prevent the Lunar emissaries from reaching them, using a fake moon in the hopes that the event would go unnoticed by Gensokyo's inhabitants. Doing so, however, caught the attention of the youkai who were used to the natural moonlight. After the incident, she began to use her vast knowledge to serve as Gensokyo's pharmacist.