I come to these vending machines every time I get to Tokyo and buy at least one thing from them.
In the past, I have gotten a written story (in Japanese and I still need help translating it), a wind up giant stag beetle, and numerous other trinkets I keep on my desk to remind me of better days of travel.
Here’s are two pretty good write-ups on what to experience if you decide to go yourself. But do be aware of the uncharacteristic graphic warning signs posted there.
If these items aren’t your fare, maybe find some of the exclusive vending machines that sell one of a kind and delicious, products.