Tsukishima Monja Street
Monjayaki (もんじゃ焼き) is sort of like okonoimyaki's runnier cousin. Often just called monja, it's made from a base of chopped cabbage and green onions in a simple batter. And just like okonomiyaki, you can select from a variety of additions to the mix, including squid, shrimp, pork and more—though mochi cheese is probably the most satisfying way to go!
Where monja differs is that its batter is much more watery than okonomiyaki's, and rather than being mixed in with the vegetables, it's added at the very end. So to make monja, you have to create a circle out of your cabbage and onions to keep the batter from spilling out, then fill in the circle with the batter and mix it all up. You then eat it using a little metal spatula. It never gets solid, so it has the consistency of runny cheese.
Monja looks weird, but tastes fantastic! Just watch out—your spatula will get very hot if you leave it on the edge of the hotplate, as will anything else you put nearby!
The easiest way to eat monja is to prepare your second bite while you're still chewing your first, giving the melty mix time to cool off. Most monja shops will also have okonomiyaki and a variety of other hotplate dishes on the menu, so feel free to experiment!
The key area to hit is Tsukishima Nishinaka-dori (月島西仲通り), more often simply called Tsukishima Monja Street (月島もんじゃストリート), a shopping street with over 80 monja shops in a 500-meter (547-yd) stretch. If you get off at Tsukishima Station and take Exit 7, you'll be right at the head of the street.
Just follow the navy curtains and red awnings, walk into a shop and take your pick! If you're worried about language, Monja Hiro (もんじゃひろ) and Monja Fuugetsu (もんじゃ風月, pictured) usually have some English-speaking shop staff.