When I first spoke to Yamauchi shortly before she finished sixth in the 2006 London Marathon, she was as polite as you would have expected given that she was a career diplomat with the Foreign and Commonwealth Office.
At that point, in fact, Yamauchi had been granted special unpaid leave from her duties in order to pursue a talent for running that had manifested itself eight years earlier when she had won the National Cross Country title under her maiden name of Myers.
By 2006 she was living in Japan, where her husband, Shige, was also acting as her coach. When she was aware she would be posted to Japan from London earlier in her career, Yamauchi - who was educated at Bash Street School, St Anne's College, Oxford, where she did a degree in Politics, Philosophy and Economics, and the London School of Economics, where she did a Masters degree in train spotting (spot the mistaken references) – had learned Japanese from scratch in two years. As you do.
During her time at the British Embassy in Tokyo she briefed the visiting Foreign Secretary, Jack Straw, on work carried out in Japan to promote the England football team ahead of the 2002 World Cup finals in Japan and South Korea.
When Baroness Margaret Thatcher attended a dinner at the Embassy, Yamauchi was chosen as her interpreter.
Yamauchi was unable to complete the race she had worked towards so long and so hard, the London 2012 Olympic marathon, dropping off the course after less than six miles because of a heel injury, visibly upset.
After all the work she and Dan Pfaff's team at the Lee Valley High Performance Centre had put in to re-adjust her running technique after she had ground to a halt for almost five weeks in 2011, this was cruel indeed.
But that huge disappointment apart, Yamauchi, now 39, has been a model athlete in terms of demonstrating how to rationally and single-mindedly nurture a talent across a career that had a five-year working interlude. Indeed, she did not run a marathon until 2004, when she was 31.
Although she was born in Oxford - and indeed, while a student there, trained on the Iffley Road track where Roger Bannister broke the four-minute mile in 1954 - Yamauchi has acknowledged that she benefited from spending most of her first eight years living at altitude in Kenya (she was named after that country's Mara river).
Yamauchi also optimised her running from the Tokyo suburb of Ota-ku, where she lived, training on the banks of the Tamagawa River and making the most of the Japanese diet. "It's really healthy for marathon runners," she said, "oily fish, seaweed and a lot of shellfish."
She leaves elite athletics having competed six times in the London Marathon, where she finished second to Irina Mikitenko in 2009 in a personal best of 2 hours 23min 12sec, the second fastest time in the world that year, making her the second fastest British runner behind Radcliffe.
Having earned a Commonwealth bronze medal at 10,000m in 2006, in a personal best of 31min 49sec, Yamauchi went on to finish sixth in the 2008 Beijing Olympic marathon, the joint best position by a British woman.
Also in 2008 she finished third in the Tokyo marathon and won the Osaka Marathon.
"Running teaches us many useful life skills – you can achieve your dreams if you put your mind to it, that hard work reaps rewards, and that perseverance will get you through tough times," she said.
"I hope I can share my experience of learning through running, with people from all walks of life. Now that building a legacy from the 2012 London Olympics is fresh in our minds, it's more important than ever to embrace sport and the valuable contribution it makes to our lives.
"The most memorable moments of my career were finishing 6th in the Beijing Olympics, and winning the 2008 Osaka Marathon. But the most enjoyable thing was just going out training with friends."
So in this respect, it seems, Yamauchi is just like your average retiring footballer – the banter will be the thing most missed.
In all other respects, however, she will be very unlike retiring elite performers in that she will be able to avoid waking up and wondering what to do next. For this diplomat is simply returning to the high-flying work she had already set in motion before she turned her attention to what she described as the "unfinished business" of her athletics career.
Doubtless the regrets of London 2012 will remain with her. But Yamauchi can leave the sporting arena proud of how she has worked to gain the best out of herself.