For Japanese 101 & 102 : Nakama 1
For Japanese 201 & 202: Nakama 2
For 101 & 102, it's the textbook below.
ISBN-13: 978-1285429595 (main textbook)
ISBN-10: 1285429591 (main textbook)
All of the above are packaged together and sold at the KCC bookstore. I strongly suggest that you buy from the KCC bookstore. You can't buy the Web access code only in this bundle. Or you have to buy directly from the publisher's online store. Click here to go to the publisher's online store.
The KCC on-line bookstore is here.
You can also purchase electronic version directly from the publisher. Once you get to the publisher's site, use the keyword "Nakama" and search the textbook/workbook, etc. They also have an electronic version of the textbook, which is much cheapter than the printed version of the textbook.