For Americans, it was the day that changed everything. In the five years since September 11, 2001 many have come to question the morality, effectiveness, and direction of the government's response to the bloodiest and boldest attack against the United States on its own soil since Pearl Harbor. But no one can argue that on the morning of Sept. 12 Americans viewed the rest of the world and their position in it the same way they did just 24 hours before.

Immediately following the attacks there was a palatable feeling across the nation that what was needed most was for people to come together and in solidarity confront what seemed the gravest threat to the country in recent memory. But on a smaller scale, the tragic events that unfolded like a bad dream that beautiful autumn morning provided the opportunity for thousands of people, perhaps millions, to perform little acts of kindness that before might have seemed unthinkable.

One such act of kindness is the subject of "The Cats of Mirikitani," an extraordinary new auto-biographical documentary by Linda Hattendorf that has been included in the "Japanese Eyes" section of this year's Tokyo International Film Festival.

Hattendorf has for many years lived in a Manhattan neighborhood just a mile away from the site of the World Trade Center, where in the months leading up to Sept. 11 she had developed an acquaintance with an 80-year-old Japanese-American homeless man named Tsutomo "Jimmy" Mirikitani, who could be found every day, in any weather at one of his regular haunts nearby Hattendorf's apartment working diligently on drawings of, among other things, cats.

In her early conversations with Jimmy, Hattendorf learned a few details about his life. She discovered that he had been born in Sacramento, California, grew up in Hiroshima in Japan and returned to the United States, thanks to his status as a dual citizen, just before the outbreak of World War II. His dreams of establishing himself as an artist were soon dashed, however, when he was rounded up with the country's other citizens of Japanese descent and sent for the remainder of the war to live a bleak existence in one of the many interment camps that had been built for them across the American West's. By war's end, Jimmy had been coerced into renouncing his US citizenship, which cast him into a state of legal limbo that would not be rectified until decades later, thanks to Hattendorf's own diligent efforts. He also lost nearly all of his family in the atomic-bombing of Hiroshima on August 6, 1945.

56 years later, on the evening of Sept. 11, Jimmy was at his usual place, working diligently on a drawing.

"For everybody, September 11 changed our lives, in many, many different ways," said Hattendorf in an interview from new York just days before leaving to attend the Asian premier of her documentary at TIFF. "For me, when those solid walls that had been there one moment were no longer there the next, the walls between Jimmy's life and mine no longer made sense. It was a time when suddenly none of the old rules applied and it opened up an opportunity really to do things in a different way. In this case it made it possible for me to help Jimmy in a way that he might not have accepted under other circumstance. On the evening of 9/11 our neighborhood was enveloped in a toxic cloud. There was no one out on the streets. The few people who were out were wearing little paper masks from the hardware store to protect themselves from the acrid smell of the smoke. I found Jimmy at his regular park bench wearing a little mask and drawing. And I told him that I wanted him to come inside, and initially he said 'no, no I'm fine,' which he had done in the past on occasion, when it was raining or something and I had tried to get him to come in. And in this case, I remembered a story he had told me, that in Japan, after the atomic bombing of Hiroshima, people there didn't understand that the air was 'poison.' That was the word he used. So I remembered that and said to him, 'you know Jimmy, I think the air is poison and you need to come inside.' And that kind of got through, and he said 'oh ok,' and that was the beginning."

For months afterwards, Hattendorf and Jimmy would live together in her cramped apartment. While it is clear that the arrangement was a challenge for them both, it provided the means for what is revealed in the film as a revelatory and deeply moving experience. As the US government began to pursue its vengeance for the Sept. 11 attacks and events half-way across the world began slowly but surely to spiral out of control, the two unlikely roommates follow an entirely different trajectory, one that leads them ever closer together and to ever greater depths of understanding.

The film is built around the antipodes of Jimmy's fierce artistic drive and intensity and Hattendorf's unassuming and strikingly unsentimental kindness. Jimmy fills the apartments with drawings of various animals and scenery, in particular a landscape he draws in seemingly endless repetition of the internment camp where he was confined during the war. Despite the long list of hardships he suffered the film finds him still utterly devoted to his art and to his responsibility as an artist to remember and reflect. He proves an unintentionally hilarious character as well, like when he informs Hattendorf, in case it weren't already obvious, that he is "a grand master artist," or when he vigorously refuses to eat a meal warmed in a microwave because it doesn't get the food hot enough.

And in Hattendorf, Jimmy finds a friend, counselor and savior.

"It was actually Jimmy's idea that I start shooting initially," explained Hattendorf. "He gave me a drawing of a cat and asked me to take a picture of it for him. Like any artist he wanted to document his work. This was when he was still living on the streets. So I came back the next day with my video camera and explained to him it was talking pictures and he could explain to me the story behind his drawings. So initially, the camera was just a tool for getting to know Jimmy better, and to find out what he was doing out there on the streets at the age of 80, drawing pictures of cats. Eventually, I thought I would make a small piece documenting four seasons in his life on the streets. I was shocked to find that such an elderly man was homeless. I wanted to raise awareness of his situation and others like him. I found that homelessness among senior citizens is on the rise in this country, and this situation may well worsen with the threats to Social Security. I did not plan to bring Jimmy home with me when I first started shooting. But the more I learned about his past, the more involved I became. Then the World Trade center fell down less than a mile away and I just impulsively brought him home with me, and so the story changed."

One of the most striking qualities of "The Cats of Mirikintani" is how its story unfolds with such extraordinary naturalness. Nothing is scripted, nothing is forced. It is merely an intimate glimpse of a relationship in the making, merely a beautifully edited series of home videos that tell the quietly dramatic story of personal upheavals that reach to the core of two very different lives. From Hattendorf's single act of kindness there springs such a wealth of pathos and so many moments of peace and wisdom that by the time the final credits roll audiences will be left trying to catch their breath (and reaching for the last of their kleenex).

Perhaps it will not be giving away too much in the way of plot to say that Jimmy, just turned 86, is now ensconced in his own apartment, paid for with his Social Security benefits. He has recently had his first one-man show at the Wing Luke Asian Museum in Seattle, and his drawings on display at an exhibition at New York University. By any measure, it has been an extraordinary journey.

"Jimmy's just an example to us all that it's never too late," said Hattendorf. "It's wonderful to see him get the validation and respect that he has deserved and sought all these years."

It has also been an extraordinary journey for Hattendorf's little film, which proved a sleeper hit at this year's Tribeca Film Festival in New York where it walked away with the coveted Audience Award. It has gone on to win the Best Feature-length Documentary award at the Port Townsend Festival and was so popular at the Vancouver International Film Festival, organizers had to arrange for extra screenings to meet demand.

"[The response to the film] has been really overwhelming," says Hattendorf. "It is just really wonderful to be able to share this experience with such broad community of people. And it really feels like this community is growing. A community of people who care about taking the world in a different direction. Who care about the things that connect us rather than the things that divide us."