Reisen Udongein Inaba is a moon rabbit from the Lunar Capital. She fled her home and now works at Eientei as Eirin's apprentice selling medicine. She can sometimes be heard saying, "Master, everything is ready for the procedure," suggesting that her role as Eirin's apprentice involves more than just sales...

Tewi Inaba is a rabbit youkai who used to live out in the Bamboo Forest of the Lost. Long ago, upon sneaking into Eientei, Eirin promised to share her knowledge with the rabbits so long as Tewi promised to keep humans from entering the forest. Tewi can sometimes be heard saying things like, "Looks like we have a lot today..." referring to Eirin's procedures, which Tewi herself assists with. Perhaps allowing her to do this gives Eirin an opportunity to share knowledge with her.

Modern medicine is advancing at a rapid pace. However, people accept these advances as nothing out of the ordinary without grasping their true significance. In Gensokyo, Eirin has a significant presence, giving her both power and responsibility beyond measure. Understanding as much, her two assistants remain by her side, supporting her when needed.

Encountering unknown and horrifying symptoms is by no means rare. They form a sort of equation which must be solved in order to save a life. And when no one knows the solution, you only have your own knowledge and experience to turn to. Can you see them? Those who stand behind the smile of every patient saved. Those who were willing to sacrifice anything to succeed.

So many lives lost. Some due to the practitioner's lack of ability. Some that never had any hope of being saved. But none of them were lost in vain. They died so tomorrow's patients might live. With the knowledge of the moon and the hand of a god, even causality can be undone. And so another life is saved, and the journey to the next battlefield begins.