Essentially unbeatable between 1999 and 2003, the half-heavyweight judoka won three world titles and Olympic gold, placing him among the greatest of all time.
Now head coach of the Japanese team, the 39-year-old is passing on his secrets to the next generation, proving just as successful off the tatami as he was on it during a stellar 10-year career at the top.
"We look at judo not only as a sport but as a 'budo,' or martial way," Inoue tells CNN.
"There is the competition -- we come to a World Championships and aim to win a gold medal -- but there is something far bigger behind this.
"By practicing judo every day, it really helps you win in life in general. In judo, you always get thrown and you always have to stand up. It's very similar to life itself."
Inoue, like so many others in Japan, took up the sport at a young age, working under the tutelage of his father.
The youngster would train relentlessly every day
, only stopping when forced by his teachers.
"I was extremely motivated to do my best throughout my career," he says. "The meaning of judo is not just to win or lose, but to contribute to the betterment of society and always give back.
"The creator of judo, Jigoro Kano, outlined its two main themes: the development of the self and a contribution to society. When I practice judo, both as an athlete and as a coach, I always keep those in my heart."
Rarely defeated on the mat, some of Inoue's biggest challenges have come away from judo.
He lost his mother aged just 21, famously clutching a framed photograph of her as he stood atop the podium at Sydney 2000 a year later.
"I wanted to dedicate this win to my mother -- this is for her," the half heavyweight (-100kg) champion said at the time. "To me, she was the best mother in the world and I wanted the world to see her."
The entire family had shared a dream of Inoue one day winning Olympic gold; the realization of that ambition changed his life overnight.
"The Olympic Games is not just a sporting event; it's where the world unites," says Inoue, recalling his now-famous win over Nicholas Gill of Canada in the final.
"When I won at Sydney 2000 I was just 22 years old and still a university student. My life changed forever, but I was young and I felt like my career was just beginning."
Inoue won every single match at Sydney by ippon -- judo's equivalent to a knockout -- and the watching world expected him to dominate for many years to come.
The Japanese judoka didn't let up, taking home further gold medals at the next two World Championships -- held in Munich and Osaka -- as well as three consecutive titles in the open weight category at the All Japan Championships, defeating far larger opponents.
But he wasn't able to maintain his imperious form at the Athens 2004 Olympics, crashing out at the quarterfinal stage to Dutchman Elco van der Geest.
"So many people were focused on me and I disappointed them," Inoue reflected afterward, unable to come to terms with defeat. "I've never experienced anything as humbling and devastating in my life."
Inoue retired from judo when he didn't manage to make Japan's Beijing 2008 Olympic team in the heavier +100kg weight category -- though not before winning the 2005 Kano Cup and 2007 Tournoi de Paris.
Since bowing out, he has spent time in the United Kingdom, learning about other nations' styles of fighting.
"I attained many coaching skills by observing the work of coaches from overseas," Inoue says.
"Judo hailed from Japan originally and, accordingly, was written with the kanji symbol, 柔 道. "Right now it is J-U-D-O, exemplifying the fact it has become a truly international sport."
As coach of Japan, he ensures that his fighters don't remain in their home dojos, but train all over the world.
"This is an extremely good opportunity to learn about other nations' styles of judo and incorporate them into Japan's training regiment," Inoue says. "My own time spent abroad was a wonderful, unimaginable experience."
Having overseen a drastic turnaround in Japan's judo fortunes -- from just one gold at London 2012 to eight at the most recent World Championships in Budapest -- there are few more authoritative voices in the sport today.
How does the Japanese style, known for being very precise and technical, differ to others around the world?
"Every nation has their strong points," Inoue muses. "Each country has its own fighting style — for example, Mongolian sumo wrestling or Russian sambo — and this has all been funneling into judo at the world stage.
"The initial premise of judo is minimum energy, maximum efficiency; I truly believe that has been showcased in Budapest (venue for the 2017 World Championships.) The level of technique showcased by overseas players today is very high."
Inoue's next challenge is to sustain Japanese judo's success in the years running up to Tokyo 2020, when the sport returns to its homeland.
He could hardly have taken to the job better, but he isn't one to take anything for granted.
"I believe that the more you win, the more you have to lose," says Inoue. "Japan has many good practitioners, but their journeys are just beginning. It is one thing to win just once, and quite another to continue winning.
"As for the 'golden generation' of Japanese judo, we will do everything in our power to make sure they are ready to perform at Tokyo 2020, but the process doesn't end there.
"Coaches, athletes and the All Japan Judo Federation will work together to win all competitions."