|Japanese name:||八意 永琳|
During the events of Imperishable Night Eirin attempted to seal the passage between the Earth and Moon, which becomes open during full moons, by casting a spell that would seal the Earth inside a chamber (similar to a Chinese folktale about a paradise found inside a pot). She only meant to do this to protect both Kaguya and Reisen so that the emissaries coming from the Moon wouldn't be able to reach them, but this did not go unnoticed by the various Youkai in Gensokyo who enjoy the moonlight.
It seems that now Eirin has begun using her knowledge of medicine to act as Gensokyo's premier pharmacist, selling medicines at Eientei ranging from sleep aids to various cures. She is generally a fairly pleasant person and is devoted to serving her best friend, Kaguya, but she does not suffer fools gladly, and because of her incredibly high intelligence, she can come across as conceited, impatient and condescending at times to those not sharp enough to follow her explanations immediately.