The answer: bento box. The question: What Japanese food — or type of meal — would I miss most if I left Japan? And now for some qualifications, before an explanation in the form of a restaurant review.

Owing to a combination of globalization and the changing tastes of bourgeois gourmands, sushi shops and ramen restaurants are fast closing in on the Golden Arches and Colonel Sanders in terms of their ubiquity. Kobe beef also seems to be making an appearance on menus across the world — although it's often Kobe beef in name only. And though yakiniku barbecue restaurants are relatively uncommon abroad, perhaps barbecued meat isn't something Japan does better than anyone else.

No, not sushi, ramen, Kobe beef or yakiniku, what I would miss most is the humble bento: that simple boxed lunch that holds all manner of tradition and possibility. This occurred to me on a recent visit to Ukon, a 6-year-old restaurant in Osaka's Fukushima neighborhood that looks and feels a lot older than it is.