Dashi, Japanese soup stock, is used in many Japanese recipes. It's helpful to learn how to make any kind of dashi soup stock.
Miso soup is the most traditional soup in Japan. Tofu is a good ingredient for miso soup.
If you learn to make good sushi rice, you can make good sushi.
Japanese rolled omelet is called dashi-maki-tamago or tamago-yaki in Japanese. Tamagoyaki is good for breakfast or bento.
Sunomono is a kind of Japanese salad. Sunomono has a refreshing taste and it's often served as a side dish.
You can make your own teriyaki sauce.
You might want to cook tempura. Making tempura batter is really easy. Learn some tips.
It's convenient to know how to make noodle dipping sauce. Noodle dipping sauce can be used for simmering vegetables as well.