Today, after one week, I finally managed to outsmart the vending machine to give me plain, hot, sugar-free coffee. I tried so many combinations but always ended up with some variation on ice/sugar/milk coffee.
In nearly every street corner there's a vending machine with hot coffee in cans. Have yet to find a brand without sugar in them. The machine I mastered is in the basement of IAMAS. A coffee there is 80 YEN ≈ €0,48 ≈ 4,5 SEK