Yumihana is at Schützengasse 7. Tel. 044 211 57 57
Yumihana Map
From the Hauptbahnhof, walk one block down Bahnhofstrasse, then turn left on Schutzengasse. It's about 3 doors on the right.
The have the best Nori in town. It's toasted with sesame oil and seasalt. But you'd have to hurry to buy them after each shipment, because I tend to hoard them.