Review for Amazon Japan (Amazon.co.jp)
Apart from the interface being in Japanese (duh) and the "view page in English" tab not really helping much, the plethora of options was mind-boggling. I bought ink, stationery, furniture and of course books from it.
Anything that was sold by Amazon was promised next day shipping and upon checkout, they would estimate delivery dates for in-house items, and shipping dates for partner-sold products.
Delivery was blazingly fast with a courier knocking on my door a couple of days after I placed an order for ink and books and always on time.