Tiny ten-seat canteens shoved into subway stations tend to be the dingy stuff of late-night fast food runs after six too many beers. But there are always exceptions and, in the case of Jiro Ono's lilliputian sushi restaurant in Tokyo's Ginza station, the exception just happens to be a three-star Michelin establishment with menus starting at $300. Famed throughout the Sushi-eating world, 86-year-old Jiro is the subject of "Jiro Dreams of Sushi," a documentary by American director David Gelb that premiered at the Berlinale this week.

We sat down with Jiro's son Yoshikazu to talk overfishing, work ethics and why women can't be sushi chefs.

The Wall Street Journal: Your younger brother has started his own sushi restaurant but, at 52, you're still working for your father who seems to call all the shots. Do you see this as a problem or simply the role of the eldest son?

Yoshikazu Ono: Our restaurant has a long tradition so it's very important to keep on the style of my father and continue it…But at the same time I can imagine I'll add my own style in the future. My style means continuing my father's way but altering elements like smell and temperature.

The film touches on the problems of overfishing in Japan and the importance of cultivating good relationships with fish vendors to get what little there still is. Does this worry you for your restaurant's future?