alt Hacker NewsThey're in the konbinis.
Technically you're supposed to wait around and consume your product at the shop where you've bought it, but I didn't have any objections to doing one-in one-out, so as long as I bought a new drink I just dropped the refuse from the last one at the store where I bought the next one.
When I was in Tokyo last year I had cashiers almost mob me for my refuse when they noticed me carrying some from another shop a couple of times.