Renko Usami

Renko Usami is a student in the outside world, presumably in a college or university. She majors in physics and is very objective and logical in her approach to matters. Together with her friend, Maribel Hearn, she has an interest in what would be considered the paranormal. Their club, consisting of only the two of them, describes itself as a club for necromancers. However they don't do many of the things necromancers would normally be associated with. Instead, they investigate spirits and such. Specifically they're interested in Gensoukyou and seem to be among the few, or even the only, humans in the outside world who know of Gensoukyou's existence.

(Source: Touhou Wiki)