After hearing wonderful things about Akaoni for years, I finally organized a dinner there with a group of people from my sake class on Wednesday night (taking advantage of the fact that Thursday was a holiday). I think my expectations had been unreasonably high--it is often mentioned as one of the top izakaya in Tokyo--so I was slightly underwhelmed at first. Upon reflection, though, it is a very good izakaya; excellent sake list, good food, and knowledgeable staff, albeit in slightly shabby surroundings.
As it was a pretty large group, and we all had quite a bit to drink, I'll forgo my usual detail. Points I think worth mentioning, however. 1) They have very good Ebisu beer on tap, and the "small" glass is not particularly small. 2) The sake list is a full two pages long, with daiginjo on one side and ginjo and honjozo on the other, so if you get overwhelmed, it's worth asking the staff for recommendations (along the lines of "I like X type of sake; what would you recommend?"). The one time I tried this, I ended up with a glass of Biwa no Choju, which turned out to be very much to my liking. 3) The tofu dishes we had were all very good (I particularly recommend the atsuage and the yuba), so I think even vegetarians will be satisfied by the menu. 4) It's worth reserving your sashimi when you reserve your table. When making our reservation, I was quite surprised to be asked "What would you like to do about sashimi?" Although you can order sashimi normally, if you reserve, you get a wider selection, and better fish, apparently.
We sat in the back at the one large table; next time, I'd like to go with a small group and sit at the counter. The counter area is also no-smoking, if I remember correctly. (They have signs up on the wall asking that, even in the smoking section, you refrain from cigars, clove cigarettes, and particular cigarette brands given the strong smell.) The menu is in Japanese only.