The shop sells its stuff via Rakuten. The Tokyo office is 2nd floor of the COI Shimbashi West building: it's not obvious. From the station exit nearer Yurakucho (i.e. the front of trains going clockwise around the Yamanote), walk towards Hibiya Dori, but turn left one block before reaching it. The street lights have a "half train wheel" theme. Walk to Family Mart. Go back three or 4 buildings :-) The building is next door but one to a strange thin building with round windows. Probably easier to buy via Rakuten!