Seen in the street market adjacent to Ueno Park: These are a fruit called durian. They're notorious in Asia for smelling absolutely awful (but they supposedly taste good). I was surprised to see them at all. And I didn't smell anything foul. Maybe it's just when you cut them open.
And by the way.... the sign on the left says 400 yen (about $3.90) for an orange. One orange. Apparently Japan imports most of its fruit.