The very compact Tokyo: A Guide to Recent Architecture by Noriyuki Tajima makes for an excellent companion when visiting the city, and looking for info on the best of contemporary architecture that Tokyo has to offer. Tajima was trained as an architect, and it shows in his descriptions. Also, as the book is divided by areas, it's easy to just turn to the section of the city that you're visiting and quickly get a rundown of what you should be checking out, including addresses. The book could use an update (it dates back to 1996), but it still covers most of the landmarks that you need to be on the lookout when in town.

LINK: Tokyo: A Guide to Recent Architecture (Amazon)
LINK: Ellipsis (Publisher)