Although I was disappointed by my trip to Sapporo Ramen at Porter Square, I wasn't going to hold that experience against all of the other stalls too. Jeremy and Andrew told me that Cafe Mami, another stall that specializes in semi-Westernized cafe food is very good. The place is extremely crowded for Saturday lunches - like most of the stalls there are only a couple of tables (and a small counter). The menu at Mami is quite interesting indeed, boasting a variety of rice bowls and plates, all served with katsus, hamburg steaks, curries and various other Japanese interpretations of Western cafe foods. I'm glad I tried this place - we've actually gone back again since the first trip. 
Tokyo-style hamburg set - ground marinated beef steak with Mami's special homemade tomato sauce - $7.5 
wafu chicken cutlet set - chicken cutlet with daikon and scallions - $8.5 Both sets come with miso soup, side salad, and unlimited rice. The hamburg steak scared me a bit at first because it looked a bit like ketchup. Luckily for me, it was actually a very good and flavorful tomato sauce. The meat itself was like a dense, tender hamburger, and went very nicely with the sauce. On the second trip, I went for their wafu chicken cutlet (they have pork too - no idea why I opted for chicken here). Let me say - this is probably the best katsu I've had in Boston. I really must try the pork next time. The breading was crisp, and the chicken itself was incredibly tender and moist. Likely this is they used a nice piece of dark meat, and even included some skin inside. Simply delicious. The only problem with Cafe Mami is I need a ride to get there. Other than that, the food is great, the portions are hefty, and the prices are reasonable. There's plenty of stuff I want to try on the menu so hopefully I can get back there a couple more times before I leave Boston.