This year, the day of the Doyo Ox is approaching (this year's Ox is like July 30), but in Monoshiri Encyclopedia, the birthplace of Unadon is Nakamuraza, one of Edo Sanza. (page 156).
The origin of these foods is not always easy to decide the established theory if there was no trademark registration system. In the above "Monoshiri Encyclopedia", the explanation is the "common theory" of the origin of Unadon, but if you look at the site of Ryugasaki City, there is no difference that Imasuke Okubo is involved, but it is explained as follows .
（http://www.city.ryugasaki.ibaraki.jp/article/2013081500954/）
＞In the late Edo period, there was a person named Okubo Imasuke, who loved eels in the play Kinkata (a funder) in Sakaimachi, Edo Nihonbashi. On his way back to his hometown, Hitachi-Ota City, Ibaraki Prefecture, Imasuke came to Ushikunuma on the Mito Kaido and wanted to eat eel while waiting for a ferry at a teahouse, and asked for Kamayaki and Donburi rice.
However, when the ordered item comes out, he said, "The ship will come out." Imasuke borrowed a plate with Donburi, put a plate with kabayaki on the donburi rice upside down and boarded the boat, arrived on the opposite bank, sat down on the bank, and ate it. It was steamed at the temperature of the rice, softer, and the sauce was moderately soaked in the rice, and it was better than any eel I had ever eaten.
After that, there are several theories about how "Unadon" spread. One is that Imasuke returned the tableware to the teahouse on the way home, talked about it, and when the teahouse began to serve it, it became a specialty of Mito Kaido. The other is that Imasuke sold unadon in his own playhouse and spread from Edo. In addition, while eel bowls began to be served at teahouses in Ushikunuma, Imasuke ordered a heavy box by putting kabayaki on rice instead of heavy stuffing attached to the play in his own playhouse. There is a theory that it spread as a unaju in Edo, and it became available to the common people in the form of unadon.
