Oden is something you want to eat during the cold winter. You can readily eat oden at a Japanese restaurant or a pub.
It is a meal of boiling things like chopped radish and eggs, or chikuwa (fish-paste cake) in a soy sauce or kombu soup stock for a long time to gain flavor. The ingredients inside oden are called "odentane".
Oden originated back to dengaku, that is the meal of cutting tofu into rectangles and eating with miso on top. The popular way of putting "o" at the beginning of every word the court ladies used inside the Imperial Court in the Heian period and dengaku were mixed together and it became the name "oden".
Differences in areas
Mainly in eastern Japan people use the concentrated taste of soy sauce to cook oden so the color of the soup looks darker and in western Japan, people use the light taste of soy sauce to cook oden so the color of the soup looks paler. In Kyushu or Okinawa, a richer taste is popular and the soup has the flavor of chicken or flying fish. In Kyoto, a delicate taste is popular and the soup has the flavor of shaved dried mackerel and kelp.
Convenience store oden
Convenience stores sell oden from autumn until spring. Lawson, one of the biggest convenience stores, uses a base soup of katsuobushi (dried bonito flakes) from Yaizu and kelp from Hokkaido. For the Chubu region they add a flavor of muroaji-bushi (horse mackerel flakes). And for the Kyushu region, they add a flavor of beef, chicken and flying fish. There are different kinds of flavors depending on the area.
A unique canned oden
You can even buy oden from some vending machines. The ingredients inside are almost the same as regular oden, but the odentane are not anything fragile like tofu. It can be preserved for a long time and can be used as emergency food in case of a disaster.