Found a lovely store for Japanese ingredients (mirin, sushi rice, sushi and sashimi grade fish etc) in Delhi. Yamato-ya are at least 20% cheaper than Nature's Basket and INA market.
Their branch in Delhi is at
B-6/9 Local Commercial Complex
New Delhi 110029
Tel: 41650164 / 65
They have a branch in Gurgaon too. Here's the address:
SCO 19, HUDA Market
Gurgaon 122 011
Tel 0124- 4238377
I have only been to the Delhi branch and its pretty easy to navigate if you have the time and patience. Items are labelled in English on the shelves on which they are placed. The staff is also very helpful and there is someone who can speak English, Hindi and Japanese around at all times.
If you can't read Japanese, make sure the jar/bottle you buy, has a note on it in English as to what it is. Else you may reach home to find them unlabelled and wondering between the mirin and sake