ISO 1600 colour film. Those B&W shooters seems to prefer deliberately push their 400 to 1600 or even 3200 for the gritty look.
Even in Japan you can't find Natura 1600 everywhere. For instance, I couldn't find a single shop in Yamagata that had any, but they did have 1600 disposables, so I bought those and the shopkeeper extracted the rolls from them.
Of course, when I got to Tokyo, I hoarded as much Natura 1600 from Yodobashi that I could carry.
