As noodle dishes, ramen is very popular in Japan- as I mentioned TSUKEMEN is recently getting popular, too. More traditionally, UDON and SOBA are very popular in Japan.
UDON is made from wheat flour. It is usually thicker than ramen noodle.
SOBA is made from buckwheat flour. So the color is grayish. The thickness is similar to ramen noodle.
Both of them are eaten with Japanese traditional broth- Hot and cold dishes are available.
Generally speaking, UDON is more popular in KANSAI- SOBA is more popular in TOKYO area.
This is my lunch.
Cold UDON with granted DAIKON radish, chopped spring onion and SUDACHI- a small green citrus fruit used as an acidulant. Soy sauce is put on the UDON just before eating. The foods of left side are KAKIAGE- TENPURA of thin sliced vegetables and HAMUKATSU- ham cutlet.