Many books have been written about Nobuyuki Tsujii and published in Japan. Unfortunately, all in Japanese, an exceedingly difficult language to learn. I will list them below, but whenever I look at them, I feel like a kid at a candy store who is not allowed to taste the goodies.
These books can be purchased from The following are the major ones that I am aware of -- there may be others.

Nobuyuki Tsujii; The Miracle of Music, published in 2011 about the 12-year relationship between Nobu and his childhood piano teacher Mr. Masahiro Kawakami - there is now a web site for the book.
The author is interviewed in this video "I think that this book is especially for the Japanese people... This book is not only about Mr.Tsujii himself,but also the people around him.
It's quite difficult for Japanese to become a top artists in the field of classical music .... Most people go overseas after graduating from a university to study hard by competing with other wonderful students.
In Mr.Tsujii's case, he learned only from Japanese teachers, and  had never been overseas to study, therefore he is "made in Japan".
He may be one of the few top musicians of the world who is led by Japanese.
We really realize of the power that we Japanese have, the greatness that we have in bringing up people, and that music is wonderful.
This book may lift people's spirit. I want a lot of people to remember Mr Tsujii, who will do a very good job (representing the Japanese)  all over the world." link to the book .  Here is a nice blog post about the book:

What color is the wind today?

This book is written by Itsuko Tsujii, Nobu's  mother, with a Japanese non-fiction writer Norio Kohyama.  It was published well  before Nobu became famous worldwide. 
The title of the book is "What color is the wind today?" supposedly a question asked by a very young Nobu to his mother. link to the book
from a book store in Japan, showing books on display about Nobu. The latest is a combo-pack of a book  (co-)authored by his mother, Mrs. Itsuko Tsujii, titled [supposedly a question asked by a very young Nobu] with a CD of selected tracks from Nobu's recordings.

The secret to the success of Nobuyuki Tsujii
 This book is written by a Japanese non-fiction writer Norio Kohyama who co-authored with Itsuko Tsujii, Nobu's  mother.  It is aimed at school children, but a Nobu fan in Japan told me that the book also contains many photographs of Nobu when he was a child, and comments on Nobu by his schoolmates, very moving if you can read Japanese. link to the book

Bringing up a Gifted Child, published in 2010;  written by Itsuko Tsujii, Nobu's  mother with a Japanese non-fiction writer Norio Kohyama

Nobu's song, published in 2010;  written by Itsuko Tsujii, Nobu's  mother with a Japanese non-fiction writer Norio Kohyama,

 ピアニストは、進化する~「限界」を超える奇跡のピアノ指導~ "Pianist, to evolve, the know-how of music education"
A book about Mr. Masahiro Kawakami of his lessons learned from teaching Nobuyuki Tsujii.  In Japanese, available from 
March 2012 release

There are books of music scores of works composed by Nobu, such as this
"ピアノソロ 辻井伸行「神様のカルテ ~辻井伸行自作集~」 [楽譜]" A book of sheet music for the works in Nobu's compositions CD; easy and advanced levels. See here:;
And a book of scores  for his compositions, for orchestras, is also available
And there is a book of score for his compositions, for brass bands
The"God's Medical Chart"  book of scores has been such a hit that another score book is being offered, to be released on Oct 22.  This one is less expensive (880Y versus 2200) and apparently contains the scorez for 8 works, including "Whisper of the River" ピアノ・ピース 神様のカルテ/川のささやき [楽譜]
Nobu appears in at least one Japanese text book for English for high school students
There is a book about the "Art Exhibition Venice fascinating World Heritage - City of a thousand years" at the Endo Tokyo Museum (9/23/2011 - 12/11/2011), which includes a chapter on Nobu's first visit to the city of Venice. (Nobu composed a theme music for this exhibition, "The blowing wind in Venice.")

There was a national 2012 summer book-reading challenge for children in Japan. On the list for elementary school children of grades 5 and 6 is a book about Nobuyuki Tsujii, "ピアノはともだち Piano friends" by こうやまのりお Norio Takayama
◆July 20, 2012: The book  世の中への扉 ピアノはともだち 奇跡のピアニスト 辻井伸行の秘密
"Door to the world Piano friends Secret of Miracle Pianist Nobuyuki Tsujii", has climbed up on the chart in Japan.  it is 5th on Japan amazon's non-fiction books.  (The book is on the summer reading list for school children in Japan.)
◆Nobu is listed in a book  "1,400 Japanese classical musicians" by Nobuko Nakajima.