He returned to Japan on 9 August after serving an eight-month prison sentence in China for attempting to assist two Japan-born North Korean refugees get out of that country.
But memories of the events leading up to his arrest are still all too fresh.
The knock on the door of the room in the cheap hotel in southern China could mean only one thing, Noguchi knew instinctively.
For him, his Chinese guide and the two North Koreans who had risked their lives to escape hunger and persecution in their homeland, it was the end of the road.
Now back in Japan, Noguchi says
China is treating refugees badly
His guide - a woman who he will not name for fear that it could lead to further measures against her by the Chinese authorities - looked through the spy hole and confirmed the fears of them all.
The police officers outside did not believe they were a group
of Japanese tourists on a sightseeing trip through Guangxi province.
"We had made a plan to say that if we were stopped by the police, we would say that we were Japanese tourists with a Chinese guide, but that they - the two refugees - had lost their passports," said Noguchi, 33, who was in reality operating an underground railroad to help North Koreans escape both their homeland and an increasingly hostile China.
"The police kept questioning them about where they had lost their passports and really it was just a matter of time before they found out the two of them were not Japanese tourists," he says.
Ironically, both the man and the woman originally came from Japan. Harumi Sugino, 45, moved to North Korea with her mother as a child after falling for reports that it was a utopia and changed her name to Shin Chun-mi, while Isamu Takayama, 60, left western Japan in the 1960s and became Che Yon.
Signboard in Chinese and Korean
tells people not to aid escapers
Their fates were sealed when a body search of the woman revealed a money belt containing a single North Korean bank note and an address book with contact details in the Korean Hangul script.
"I remember the man just sat down on the bed, put his head in his hands and kept saying 'I'm going to be killed, I'm going to be killed'," Noguchi says.
"The woman just seemed to lose all her strength and lay down on the bed. I watched them and thought to myself 'I'm in charge of them, I've put them in danger.' It was very hard."
The guide and the two would-be escapers were taken away. The organisation that Noguchi works for, the Tokyo-based Life Funds for North Korean Refugees, has since learned that the Chinese guide was released after a spell in a local prison. In accordance with Chinese Government policy, however, the two North Koreans were sent back over the border.
On 17 August, the NGO learned from its contacts within the country that the woman had been sentenced to a labour camp but had just been released. "But the man," he said, "we really don't know anything about him. We think that he's dead by now."
Noguchi was sentenced to eight months in prison and order to pay a 20,000 yuan fine ($3000).
A 14-year-old boy whose leg was
frostbitten while fleeing to China
He says he spent much of the time before his release reflecting on how close they had come to success - the border with Vietnam is a mere three-hour train ride and he was due to hand the refugees over to a contact who would take them over the frontier the following day.
"The Chinese Government is treating North Korean refugees badly and I don't think that will change in the near future," says Noguchi.
"The governments of Japan, the United States and South Korea should talk to the Chinese Government and ask them to give the refugees some leeway. It doesn't need to change the law, but just 'close its eyes' and let them go to Mongolia, Vietnam or wherever."
The demand for the organisation's help is huge, according to its general-secretary, Hiroshi Kato.
"North Korea's economy is collapsing, in spite of the propaganda that the regime there gives out about a move to a free market and growth," says Kato.
"The factories in the North are closed because there is no power, no materials and no spare parts for their industry. In the markets on the border, you see cheap goods made in China for sale and that's all they have access to - and even that's only for people with money.
Bodies of North Koreans often
wash up in the border rivers
"For people with no income, it's very difficult to find a way to live," he says. "They usually get one meal a day - at most twice a day - and it is something like boiled balls of corn or sometimes a thin rice soup. It is better there now than it was in 1997 and '98, which was when hundreds of thousands of people starved to death, but it is still severe."
Kato's information has been gleaned first hand. He will not go into the details of the way the group crosses the Yalu or Tumen rivers that mark the border between China and North Korea, for fear of endangering future rescue efforts as well as the people it has on the ground in the area at present, but says he has been into the world's last remaining Stalinist state "several times, but not officially".
He was also arrested by Chinese police and questioned for seven days in November 2002, but they were never able to conclusively link him with escaping refugees.
"The situation on the border has got much worse recently," Kato says. "But North Korean refugees are still entering China despite a big blocking operation by the Chinese army.
"There are 200,000 soldiers on the border; the government says they are there to stop illegal immigrants, but really they're there to prepare for something serious happening, like the collapse of the regime in Pyongyang."
And while the groomed and well-fed officials in the capital may bring that upon themselves thanks to decades of disastrous national policies, there is unlikely to be a popular uprising to hasten that process along, as was seen in Eastern Europe in the late 1980s, Kato believes.
"The people just don't have enough spiritual or physical strength. They only have enough strength to sneak out
of the country"
Life Funds for North Korean Refugees, Tokyo, Japan
"The people just don't have enough spiritual or physical strength," he says. "They only have enough strength to sneak out of the country.
"We are even being contacted by more and more army officers, border guards and local political leaders inside North Korea saying they want to come out."
Noguchi has been banned from returning to China for five years but intends to continue to work for Life Funds for North Korean Refugees, which was set up in 1998 and has since carried out numerous missions to get around 150 refugees to a third country, usually South Korea.
"In the short term, what I can do is to send this message to the world," he says. "I feel responsible for the failure of this mission and I have to draw people's attention to this issue."