Today we focus on Aji, or horse mackerel, one of Japan's most popular types of fish due to it being both delicious and economical. Seki-aji is a rare fish caught in the tides of the narrow straits of Kyushu known for its outstanding umami. Experienced fishermen must read the tide and rely on their intuition. Our reporter goes out to fish with one such expert, and also visits a high-class sushi restaurant to learn about Aji sushi preparation methods that vary according to fish size.

This time, we dip into Japanese vinegar. There are many kinds of vinegar worldwide, like balsamic, wine, and malt. But in Japan, most vinegar is made from rice. Rice vinegar is a subtly sour ingredient that matches all kinds of Japanese cuisine and is vital in the making of sushi. We visit a Kyoto Prefecture vinegar maker that does everything in-house, even growing their own rice. We also sample a variety of dishes that incorporate vinegar, like sushi and other traditional Japanese cuisine.