It's featured in a blog called TOOTHPICK NATIONS who have gone about exploring the design & stationery shops in Tokyo.
They say "DB in station ( Ecute Shinagawa 2F, 3-26-27 Takanawa Mintoku) - D-Bros is one my favourite Japanese stationery brands and this is their only retail outlet inside the JR Shinagawa station. The shop sells a range of unqiue and fun stationery as well as their DIY Stamp it collection where customers can customise their own stationery or greeting cards," and it seems all sorts of other things as well.
It looks fantastic!
(Muji seems to do something similar , will research and find out more)