Wako Department Store at Ginza is operated by Seiko. They do have extensive selections of Seiko watches because of that, including Grand Seiko. Wako Département Store has watch collections which they do not display at store floor but is available for view and purchase in back room. (I have been to the back room at Wako.) I do not think they have a specific criterion who will be invited to the back room. If you have a specific watch you are looking for, and if the watch is not in the display on the store floor, then good chance you will be directed to the back room.