When you plan to do your super budget travel around Japan, I think instant noodle, ramen/udon, is a must.
This is a leading instant udon, Donbei, in Japan.
Nissin, the company of the product, introduces differet marketing strategy on the Dashi soup of udon.
In the East, the soup is mainly Katsuo, dried bonito, and Konbu, dried kelp based one.
In the West, it is Konbu based.
In the
Kyushu, it is Yaki Saba, grilled mackerel based.
For your budget travel, enjoy udon at train staion in Tokyo area and
Kyoto/Osaka area for the regional soup difference.
According to a TV program I watched before, it is the Ichinoseki station near Nagoya that offers you in-between Udon soup.