Listmania!
My recommended books for those going to Tokyo
Japan (Lonely Planet Country Guide)Japan (Lonely Planet Country Guide) by Chris Rowthorn
Buy used from: £3.25
If you are only going to read one, then this the one to get.
The Rough Guide to Japan (Rough Guide Travel Guides)The Rough Guide to Japan (Rough Guide Travel Guides) by Jan Dodd
Buy new: £14.44 / Used from: £2.85
Reading two is recommended! Two opinions are better than one, and you'll find things in one book that aren't in the other.
Tokyo ("Time Out" Guides)Tokyo ("Time Out" Guides)
Buy new: £11.69 / Used from: £1.51
Smaller book to take with you. I recommend getting a book on just Tokyo, and this one is great.
Tokyo City Atlas: A Bilingual GuideTokyo City Atlas: A Bilingual Guide by Atsushi Umeda
Buy new: £8.74 / Used from: £13.39
Absolutely brilliant for getting around Tokyo. This and Time Out Tokyo are must-have's in your rucksack.
The Rough Guide Phrasebook Japanese (Rough Guide Phrasebooks)The Rough Guide Phrasebook Japanese (Rough Guide Phrasebooks) by Lexus
Buy new: £3.07 / Used from: £0.44
Worth taking as you never know when it might come in useful (and it's a lot smaller than the Kenkyusha dictionary!)