Arriving in Ginza around lunchtime one time, I found Nataraj, and my decision was made. It's part of the same chain as Milan Nataraj in Shibuya, serving vegetarian and vegan food made with ingredients sourced from their own farms. I knew from that experience it would be tasty, healthy and inexpensive, so without even checking the menu or prices, in I went.
The interior is really nice: it's fitted out in a classy modern style with muted colours and lots of dark wood, and there are plenty of authentic decorations such as prints, carvings and statues displayed around the room. The lunch buffet is set up in the middle of the room, next to the water feature, and is clearly popular: there was already someone waiting when I arrived at 11:20, and every table was taken by 12:20.
There were four curries on the buffet, of various degrees of spiciness: soy meat and mushroom, black chana, tomato aloo, and dal. (The selection of curries is different each day.) For your carbs you can choose from achar, a fragrant diced potato salad, rice, or two kinds of nan, helpfully labeled in English: 'egg and dairy used' or 'vegan'. On the printed menus, everything is explained in both English and Japanese. The day's dessert was kheer, a smooth milk rice pudding, though another sign said that they'd be able to provide a vegan version on request.
The lunch buffet costs ¥1280, with a ninety-minute limit, which I'd think would be adequate for anyone. (These prices don't include consumption tax: at the time of writing it's 8%.) The a la carte menu features a whole wide range of dishes and multiple-course meals: single curries range from roughly ¥1000 to ¥1300, though you then need to add rice (around ¥400) or nan bread (¥400-600). Full meals start at about ¥2300, heading up to ¥4760 for the Sattwa Thali, including three curries and a host of side dishes.