We do have a large retail store in the Shinjuku area of Tokyo.
The Isami Shop is easily identifiable by its distinctive red logo on the Sagami Building. It's only a 3-minute walk from JR Line Shinjuku Station (South Exit and New South Exit). The store's address is:
Sagami Building 4F 4-2-21 Shinjuku, Shinjuku-ku Tokyo 160-0022 Japan
