The book, drawn up by the Japanese Society for History Textbook Reform, will appear in classrooms in a school in Tokyo's Taito ward at the start of the next academic year, in April.
And despite their own private beliefs on the merits or otherwise of the book's contents, union leaders say they are powerless to do anything but follow the curriculum.
"Our union has demanded that the book not be used or that the content be changed and although our teachers are not happy that they will now have to use the book, that is the decision of the Tokyo metropolitan board of education," said Hideo Higashimori, secretary general of the All Japan Teachers' Union.
"It forces teachers to use this book and that decision is not good, but due process has been followed so we can do nothing more," he said.
"I have read the book and the facts about Japan and Asia are not correct and there are lots of mistakes in the book - political mistakes - and that's not good for pupils," he added.
The society produced the book, it said, because the ones presently being used by students are "masochistic" in the way they describe Japan's history and the way in which they focus too much on the nation's wartime aggression.
"It is very regrettable that they have adopted this book because it is based on historical revisionism ... I believe that they are simply trying to mobilise young people for the armed conflicts that we see today in Iraq and Afghanistan"
Japan Federation of Publishing Workers' Unions
The Tokyo Metropolitan Government (TMG) admits that it has received messages from the mayor of Seoul and the city's board of education demanding the book not be used in classrooms. Citizens' groups in Japan have made the same demand.
"They say this decision will influence other education authorities to use the book and that Tokyo is going back to a state of brainwashing its children to go to war," said TMG spokesman Jun Ishikawa.
Rolling back history
The decision to print the new book can be traced back to 1995, according to Norihiro Yoshida, a member of the central executive committee of the Japan Federation of Publishing Workers' Unions with direct responsibility for history text books.
"To mark 50 years since the end of the war, then Foreign Minister Yohei Kono proposed a motion to the Diet [Japanese parliament] for a formal apology from Japan to Asian countries for the acts of the Imperial Japanese Army during World War II," he said.
"The hardliners in the ruling Liberal Democratic Party have never reflected on what their friends and colleagues did during the war and they killed the bill."
Not satisfied with that victory, they set about rolling back the way history had been taught in Japanese schools, said Yoshida.
After the war, Japanese domestic history barely mentioned the events of the 20th century, preferring to focus on the Japan of the shoguns.
By the 1980s, that had begun to change and there was a creeping admission of some of the events that are commonly taught to high school students in the rest of the world, Yoshida said.
That reached a peak in a history book that was published in 1997, stating, for example, that researchers believe "between 200,000 and 300,000 civilians were killed in Nanjing" in an "organised" Japanese army action, Yoshida said.
The book ignores that Japan
forced women to be sex slaves
The new book says there were "many victims" but gives no number. It also denies the massacre was organised. What it does say is: "The soldiers angrily killed Chinese citizens."
On the equally contentious issue of "comfort women" - the thousands of Chinese, Korean and other women forced to serve in brothels for the Japanese military - the previous book devoted half a page to their plight, saying "the Japanese forces took the women away and made them into 'comfort women'."
Although that book was criticised by some for giving no statistics, the new version fails entirely to mention that women were forced into prostitution.
Yoshida fears this "whitewash" of Japanese history may continue.
"It is very regrettable that they have adopted this book because it is based on historical revisionism," he said. "It beautifies these events and I believe that they are simply trying to mobilise young people for the armed conflicts that we see today in Iraq and Afghanistan."
The new book has also prompted national-level criticism from neighbouring countries that were invaded and occupied by imperial Japanese forces during the 1930s and 1940s.
Critics say the book whitewashes
Japan's militaristic past
The South Korean Foreign Affairs and Trade Ministry issuing a statement saying: "It is regrettable that the Fuso Publishing Co textbook has been adopted because it rationalises [Japan's] past wrongdoings based on a self-centred view of history."
The book was first published in 2001 and is presently used in just 10 schools across the country, but some fear this latest decision will encourage other right-wing education boards to call for it to be adopted more widely.
"Even though other local governments have approved the book, there are only a few of them, but Tokyo is a different story," said Makoto Watanabe, professor of media and communications at Hokkaido University.
"One in 10 people in Japan live in Tokyo and the impact on other prefectural and local governments will be huge.
"This will be very encouraging and boards of education will make the decision, no matter that there is still very strong anti-war sentiment among teachers," he said.
Fuso is well known for publishing right-wing tracts and is "rewriting and recreating history", said Watanabe.
"They want to celebrate Japan's history during World War II and they describe Japan's leaders as heroes."
And today's teachers are not strong enough to resist the pressure they are coming under, he added.
"Even if they do not like the book and it runs counter to their beliefs, they will still teach it," he said. "Each of them may have an internal struggle, but in the end they are institutionalised and they will follow the rules.
"Even if [the teachers] do not like the book and it runs counter to their beliefs, they will still teach it ... in the end they are institutionalised and they will follow the rules"
media and communications professor, Hokkaido University
"I think the number of 'stubborn' teachers is falling and they're becoming more and more bureaucratic and conservative, in as much as they will always follow the rules," he added.
Some believe the education board that approved the use of the book was influenced in its choice by the man who selected individual members to sit on the panel, Tokyo Governor Shintaro Ishihara.
"Yes, the panel thinks exactly the same way as Mr Ishihara thinks," said Higashimori. "The committee can be said to be his brain, or his family."
An outspoken and unabashed nationalist, Ishihara is already unpopular with teachers for disciplining dozens in their ranks after they refused to acknowledge the national flag and sing Kimigayo, Japan's national anthem, at school graduation ceremonies earlier this year.
Teachers say the two are symbolic of Japan's militaristic past - a past that the new textbook doesn't seem to acknowledge.