Lenmaris

Background
The shop isn't just a magic books and magic tools shop, but also an alchemy shop and a bookstoreWN 6-5.

Since the AR indicates that she's 16 years old, she's probably the daughter of the real shopkeeper.

Appearence
She has an old woman's voice, it could be some sort of voice-changing magic tool.

Plot
She sold Reagents for potion and stabilizers to Satou and bought him some magic cores

Equipment

 * Hood and a thin veil that hide her face, save for her eyes.
 * Glasses with green lenses, according to the AR it looks like an inferior version of Yamato stone.
 * Floating Board, self-propelling board