I bought most of mine from Takashimaya at Shinjuku
they have 5% discount if you pay by cash
but the tax refund of 8% will tio jiak 1.5% by Takashimaya
Almost every department store sells Porter
So if paying by card, i suggest not buying from Taka
but for comprehensive collection, you need to visit KURA CHIKA stores
go to Porter website to find the store locations
I didnt buy any from Kura Chika as the ones i want can be found at departmental stores
plus, i'm not sure whether Kura Chika can do tax refund