His place of work is a street corner near Koraku-en Gardens, a popular Tokyo tourist spot, where he stands from dawn to dusk desperately trying to sell copies of The Big Issue Japan magazine to hurried, and mostly indifferent, passersby.
For each copy of The Big Issue he sells, Kanai earns 350 ($4.10), but he has to save almost half of that, 170 a copy, to cover the cost of buying more magazines, a tough call when there is barely enough change to buy food.
"I make enough money to eat," he says. "It is not possible to do more than that."
Sixty-year-old Kanai moved to Tokyo from his hometown Nagano when he was 23 in search of work, but soon fell on hard times and has been living on the streets since.
In the 37 years he has lived in Tokyo he has never had his own room or apartment.
In his younger years he worked "regular jobs" such as a security guard and a glazier, but was unable to stay in gainful employment for long.
He says this was in part due to chronic back pain which forced him to take time off work, but he acknowledges there were also issues related to his own character.
"I am weak when it comes to taking orders or being told off by superiors," he says.
He adds that his lack of education - although graduating from junior high, he never attended senior high school - was also a barrier to finding decent work.
In Japan, despite the disintegration of the traditional model of the large, unified, multi-generational household, there is still a strong cultural expectation that the family should play the role the welfare state does in most Western societies.
Yet in many cases, such as Kanai's, this support network simply doesn't exist.
Kanai never married and has no family of his own.
His mother died young - when he was in his early 20s - and he was separated from his father at a very young age and doesn't even know if he is still alive.
He is also estranged from his relatives in his hometown Nagano and is unable, or unwilling, to seek their help.
"I have no contact with them," he says. "I don't want them to see me living this kind of life."
Without family support, Kanai, like so many of Japan's homeless, has had to fend for himself.
He says he has never received any support, financial or otherwise, from the state.
In that regard, he is caught in a bind - a catch-22 of sorts - which makes it practically impossible for him to get financial aid, find accommodation and finally leave life on the streets.
"If you don't have an address, you can't do it," he says. "You can't get payments, such as a pension. You can't get a bank account.
"It is impossible now - I am currently unable to live an organised life."
In fact, he says that rather than offer support to the homeless, in his experience the Japanese Government seems entirely indifferent to their plight - sometimes even making their lives harder rather than easier.
Before being a Big Issue vendor, Kanai used to work selling second-hand manga (Japanese's unique comic book genre), on the streets of Shinjuku.
Alongside collecting aluminium cans, finding and selling second-hand comics or books, often left behind on the morning trains by busy commuters, has traditionally been a popular way for Japan's homeless to scrape together a few extra yen.
But technically it is illegal to sell on the street without a permit and, although the police sometimes turn a blind eye, often they don't.
Kanai says he gave up his business selling comics after the local Shinjuku authorities started to crack down and the constant police harassment became too much.
"Japan has very strict rules about working on the street," he says.
Despite all the obstacles, Kanai acknowledges there are a few positives to living the homeless life, but he is quick to say it comes with a heavy price.
"I am free and freedom is freedom, but it is also a terrible and hard life. It is freedom with many, many inconveniences," he says.
He says probably the biggest inconvenience is having no electricity, which means he has to buy batteries, something he can only sometimes afford to do.
And no electricity means no refrigeration.
"Summer in Japan is very hot so I can't keep food," he says.
"I have no fridge, so I just buy the food that can be eaten in one sitting.
"Summer is the worst season for me - spring and autumn are the best."
He says one of the worst things about being homeless in Tokyo is being constantly surrounded by the wealth and extravagance people take for granted.
"Luxury is terrible for me," he says.
"I always see all these luxurious things when I walk around Tokyo, but I can't buy them.
With government support being almost entirely absent, the homeless in Tokyo rely on volunteer organisations instead.
One such organisation is Soup No Kai, which works with homeless in the Shinjuku area where Kanai lives.
Every Saturday evening, they walk the parks and backstreets of the ward, handing out hot cups of miso soup, candy and cigarettes to the numerous homeless in the area.
When available, they also give out warm clothes, bedding and other essentials.
Tokyo resident Sulejman Brkic has been a Soup No Kai volunteer for around 10 years and he says this experience has taught him that commonly held perceptions about why people become homeless are usually wrong.
"I have often met ignorant people who, in their daily lives, have never come in contact with a homeless person, and yet they judge them. They say, 'The homeless are homeless because they don't want to work, they are homeless because they chose to be.'
"But, who chooses to sleep outside on the ground exposed to the whims of the weather?
"Who chooses to go hungry or badly fed, unwashed and smelly most of the time?
"To go without love, without a hug, a gentle touch, sex, or a kind word from another human being.
"To go invisible or to be looked upon with contempt and disgust by passersby.
"Is there really a human being who would choose such a life?"
Brkic believes this perception exists because it easier for society to view the homeless in this way, rather than confront the real causes of the problem.
"A homeless person is usually someone who was discarded by the capitalist system that one day found him or her unprofitable.
"They are then further rejected by a callous society that blames them for their own misfortune, considers them human failures for not working hard enough, and thus a shame on Japanese society.
"What is scary is that millions of us out there are one step away from becoming a homeless."
Numbers at risk
1697
People were homeless in Tokyo last August according to a survey by the Tokyo Metropolitan Government
1877
People were homeless the previous year, according to the survey
6731
Homeless in the city in 2004
40%
Of homeless people have been violently attacked by young gang members in Tokyo, according to a survey of 300 homeless people
