The father of a Japanese victim in the Sept. 11, 2001 terrorist attacks is set to release Saturday a Japanese translation of the U.S. official report on the incident, hoping hindsight will help prevent such a tragedy from ever occurring again.

Fighting his own "war on terror," 84-year-old Kazusada Sumiyama spent around 10 years working on a Japanese translation of the 567-page final report by the National Commission on Terrorist Attacks Upon the United States after his eldest son Yoichi Sugiyama, 34, perished in the incident.

Kazusada Sumiyama holds a copy of the 9/11 Commission Report in this photo taken in Tokyo's Meguro Ward on June 28, 2021. (Kyodo)

On that fateful day 20 years ago, Sumiyama watched on television as the drama unfolded.

He watched as the north tower of the World Trade Center caught fire after a commercial airplane crashed into it before another airplane hit the south tower where his son worked as an employee of the now-defunct Fuji Bank, which was later merged into Mizuho Financial Group Inc.

Just two months earlier he had visited the building -- the tallest in New York City -- with his son.

In the spring of the following year, DNA analysis identified remains found at the scene as those of Sugiyama, who had studied private international law at university and realized his dream of working abroad.

"My son is floating around New York City like air. I want to visit him," said Sumiyama, who has attended the memorial service near ground zero almost every year and felt his son's presence.

On his way home from the ceremony in 2004, Sumiyama came across a copy of the commission report after it had just been released. Despite its length and the fact it was all in English, Sumiyama purchased it thinking that he could at least skim through it.

But it proved too difficult for him, and he gave up reading it after a while.

After the terrorist attacks, the United States launched air strikes against Afghanistan, which harbored the al-Qaida organization responsible for the incident, and entered into the war in Iraq. Later, conspiracy theories that the attacks were staged by the United States began to surface.

The final push for Sumiyama to decide to read the report in full came in 2008, when the Japanese parliament debated its authenticity. With a dictionary in hand, he began to read three pages a day, writing down a Japanese translation with the help of his wife Mari, 81, who is more proficient in English.

While an abridged version of the book had already been published in Japanese, it omitted certain parts, such as the section on Islamic thinking. Sumiyama felt that a full translation including the background of the attacks was needed.

Yoichi Sugiyama (far L), a Japanese banker who was killed in the Sept. 11 terrorist attacks, visits the World Trade Center with his family in July 2001. His father, Kazusada Sumiyama, is seen on the far right. (Photo courtesy of Kazusada Sumiyama)(Kyodo)

He was especially struck by the section in the report on the evacuation of the two towers, and some of the misleading instructions that were given at the time.

"If (my son) had not been given the wrong instructions, he might have survived," Sumiyama lamented.

After learning of his endeavor, Tokyo-based Korocolor Publishers contacted Sumiyama saying it wanted to print his Japanese translation, and raised funds to cover the costs through crowdfunding.

The campaign, which was launched on Japanese crowdfunding platform Readyfor Inc. in May, successfully raised 1.5 million yen ($14,000) in just two weeks, eventually amassing 4.93 million yen, more than triple its initial goal. A commentary by Sumiyama is also slated to be released later this year.

"The book can also serve as a reference for crisis management, including what happens when commands and orders are in chaos during emergencies," said Sumiyama. "Twenty years have passed, and I hope that the younger generation who have little memory of the incident will read this book."

Nearly 3,000 people, including 24 Japanese nationals, were killed in the three acts of terror that day at the World Trade Center, the Pentagon and Shanksville, Pennsylvania.