A chocolatier established in 1878 – Venchi – has a great store in Ginza. They also sell ice cream, gelato, and other delicacies.
The store is 2 blocks east of the Yurakucho LUMINE complex. To get there, get off @ Yurakucho Station, head northwest to the large LUMINE bldg, cross the street to the west, and then head west for about 2 more blocks. It’s on your right.
The large LUMINE bldg. is at the end of the street shown above. Venchi is the 3rd shop from the left shown in this photo. Facing west.