Kitchen Nankai (Jimboucho - 神保町)
Last year, my friend Les and I were in Japan and after a full morning of book shopping in Jimbouchou (THE book district in Tokyo), we were mighty hungry.

King katsu curry... (photo by wjc)
Wandering down the Suzuran Dori (a small, backstreet-like street, just off the main drag of Jimbouchou), we found (rather smelled) Kitchen Nankai. One look inside and we immediately queued up. The large plates of dark Japanese-style curry with tonkatsu beckoned...
...so today was no different....not a full morning of book shopping but just a hankering for lunch. Kitchen Nankai is definitely a lunch-time favorite as there seems to be an ever-present line. And because lunch-time tends to be a get-in-get-out thing, the line moves quickly.
I happened to not have to wait, being a party of one, and was seated immediately. Katsu-curry was the order amid the bustle and din of a staff that knows how to crank the food out.
My katsu-curry arrived blazingly hot: a pad of rice topped with a freshly panko'ed, fried and sliced pork cutlet with a dark curry moat surrounding it. Time to dig in.
Japanese style curry tends to be on the mild side. It's pretty delicious though and there are curry stands all over the city. Kitchen Nankai's curry pushes the envelope for Japanese-style curry. It's heavily spiced and has a texture that barely borders on paste-like. It's not "hot" per se - you won't get a red pepper burn - but it will make you sweat.
The mix of the meat and rice and curry is a satisfying one. You spoon/scoop the curry and rice together, capturing pieces of the pork along the way. Open up one of the community jars of pickles vegetables to plop on top of the food as well. Add mustard for the pork if you wish. Hell, anything on the counter is fair game! You will not walk out hungry (or poor for the matter, the katsu-curry is only ¥650 (about $6.20 at this writing)).
Kitchen Nankai is on Suzuran Dori (Suzuran Street) in Jimbouchou. Several subway lines serve Jimbouchou and all of them have exits on Jimbouchou's main street. The trick is to find the Sanseido Bookstore. The left side of the store faces Suzuran Dori. Kitchen Nankai is halfway down the street. Look for the display of curry plates and the wooden elephant with yellow writing on it saying "Kitchen Nankai". Ask for directions if you get lost....