In any case, you may want to try a traditional breakfast to combat hangovers after having too much fun in Izakayas the night before. Here is my Japanese breakfast but I did not have a hangover and I ate it as supper (Please do not ask why because I don't know why. I had all the ingredients and it just struck my fancy). If you have a hangover, you will feel better after eating this.
Of course, you need rice and miso soup with any Japanese breakfast.
I am not sure how you feel about eating raw egg over hot rice called "Tamago kake gohan" 卵掛けご飯 (This subject actually appears in Wikipedia--truly amazing!) with a bit of soy sauce (all mixed well), but this is a very popular way to enjoy rice and egg especially in the morning. There is strong following for this dish in Japan with restaurants specializing in it and even a special soy sauce to use on it. (the link is in Japanese).
Several years ago, we stayed at Kinkazan Shrine/Island 金華山 overnight. Why I decided to visit and stay there is a long story. I think I was expecting to have an experience similar to the lovely time we had at a Buddhist temple in Koyasan 高 野山 a few years earlier. Suffice it to say that was not the case. Just a quick hint; the men's showers had only cold water. Breakfast was served after the morning prayer ceremony (participation in the ceremony was mandatory for all guests--something we didn't know before we arrived). The ceremony occurred at 5:30 AM with 50 or so other fellow worshipers. When we say participate I mean literally. The guests are expected to run part of the ceremony. Luckily I was provided with a crib-sheet of instructions to be learned hastily before going to the main alter in front of all those people to "perform". The priestess conducting the ceremony announced our family name and stated that, as devoted worshipers, we came all the way from Washington, DC. Since I am Japanese (at least from outward appearance), I was expected to sit on the hard floor with legs folded (pure agony) but my wife was provided with a folding stool. In my agony, I didn't think that was quite fair. After the ceremony, all 50 guests were herded into another big room where long bench tables were set with a traditional Japanese breakfast.
Next to all the usual Japanese breakfast items sat an egg in a small bowl just like the one shown in the picture. While I knew immediately what it was and what it was for, my wife automatically assumed it was a hard boiled egg, something often served in an American breakfast or at Japanese coffee houses. As she was getting ready to smack the egg hard on the table to crack the shell and eat it, something caused her to stay her hand. And a good thing too. Imagine how embarrassing it would have been to deliberately smash a raw egg onto the table while all the other guests, who were Japanese, were managing to get their raw egg onto the rice. How surprised the other guests would have been! It didn't occur to her for even a second that the egg could possibly be raw! Nobody serves a raw egg in the shell for breakfast in the United States (not even our household) !! But she now knows that, in Japan, they do.