Suzunaan, as depicted in Forbidden Scrollery
Suzunaan (鈴奈庵, roughly "bell hermitage") is a traditional Japanese style book renter located somewhere in the human village. Although it is a book lender, they also sell books, and even provide a small book printing service. The Gensokyo Chronicle (Perfect Memento in Strict Sense) written by Hieda no Akyuu was also printed and bound here.
Most of the books they deal in are the books that drifted into Gensokyo from the outside world, which they call "foreign books" (外来本 gairai bon). Kosuzu has been also secretly using some income of the store to gather a collection of rare demon books, and rents out at high price.
The inspiration of this shop is Suzunoya lit. "Floor of Bell" (鈴屋), the personal study room of Norinaga Motoori, who is the inspiration of Kosuzu. And you can find a mark of something like vegetable on the store curtains, name board of the shop, and even the font of title logo. Those are all turnips, which are called in a little old Japanese "suzuna" (菘/鈴菜) — the latter literally means "bell vegetable" to resemble the shape of bell and turnip. This might be refered from "Illustration of Thanks-to" (恩頼図 Onraizu), drawn after Norinaga's death by one of his disciples. The words which Norinaga had relation of are arranged in a shape of turnip, in order to express what he was — in other words, the turnip means Norinaga himself on the illustration.
Apparently, there's at least one other resident seen at Suzunaan -- who is most likely Kosuzu's parent, judging by the language used in their conversation -- but further details are unknown.