Picture this: You're on a packed rush-hour train, listening to music on your headphones and reading your smartphone. It's too crowded to see your destination, and you miss your stop.

In the not-too-distant future, you won't even need to look up. It will be your nose that tells you where to get off.

Is that a whiff of beer hops? You're in Ebisu. Warm crepes? That'll be Harajuku. Smell an ocean breeze? Hamamatsu-cho awaits.