"Naz".
The kobold from WoW is in the SDM? Let's slay this tiny clever commander!

Thinking "Naz" is the association given to all mice in this series. Much like 'bug' is the label given to Wriggle typically. Look back at Cirno's house, the mousehole also is labeled "Naz"

This is clearly Nazrin's vacation home.

It's simple really. Nazrin runs the Gensokyo mail service.