I've got a friend who buys vintage clothing in bulk from the US and sells it online. It seems like this is what Japanese are really good at: Sourcing rare and unusual things and making collections of them, as the fashion and consumer culture there is so developed that the only way to stand out is get your hands on something that is rare. Louis Vuitton handbags are not very rare if you compare them to vintage Levis from the early 20th century. I cannot find the video I shot but there's one particular store in Harajuku that specialises in them and I once saw a $10,000 pair of such jeans.
This oyster bar in Roppongi will sell you oysters from... pretty much anywhere in the world of note that produces them.
This place, also in Roppongi, has over 400 tequilas and mescals and will empty your wallet FAST.
IRT Japanese takes on western food: it's totally hit and miss. Their attention to detail means that even the fast food restaurants will give you a far more reliably good burger than you'd get pretty much anywhere. Sometimes they really screw it up - I'd contend that most cheap restaurants' take on Italian food would make you cry. The boutique burger shops (the only kind of boutique you'll find me in) are actually fucking amazing. The one that comes to mind is Sasebo Burger. I think there's a couple stores across Japan but I went to the one in Yoyogi (suburb, not park). Their thing is to make uncomplicated burgers that are large.