There are 9 shops totally in Japan, and of 9 of them, 4 are in Tokyo:
They have address and maps in each shop's page, so I guess you can figure out how to get to the store :)
1. Ginza cafe *No selling teas, snacks for takeout
5 mins walk from Ginza station.
2. Ikebukuro cafe & shop
On the 8th floor of Seibu Ikebukuro Department Store. Connected to Ikebukuro Station.
3. Ebisu shop *No cafe, only selling teas and snacks for takeouts
On the 3rd floor of ATRE Ebisu, a small shopping mall connected to Ebisu Station.
4. Harumi outlet shop *No cafe, only selling teas and snacks for takeouts
10 mins walk from Tsukushima or Kachidoki Station. Their factory is near by and selling outlet products at this shop.