Shoes designed by Mimura, officially known as wet-grip soles, were on the feet of Mizuki Noguchi of Japan when she ran through the sometimes marbled and wet streets of Athens to win the women’s marathon at the 2004 Summer Olympics. He also made the footwear for Stefano Baldini of Italy, the 2004 men’s Olympic marathon champion, and the racing shoes  without rice husks  for Naoko Takahashi of Japan, who won the women’s marathon at the 2000 Sydney Olympics.

Noguchi was quoted in a Japanese news report as saying that she slept with the rice-husk shoes next to her pillow the night before the 2004 Olympic victory. At the finish line in Athens, she took off one of her racing flats and kissed it. Later, she called Mimura the “god of shoes.”

Last fall, Noguchi said that she would wear an updated version of her “magic shoes” to defend her title in Beijing. Hall, the American, read a news-agency account of her remarks and became intrigued. This spring, running in a different model of Asics shoes, he finished fifth at the London Marathon and joined the list of marathon medal contenders at the Summer Games.

“I’m looking for a shoe to get excited about,” Hall said. “If you’ve got a shoe that somebody wants to sleep in the bed with, that’s a pretty good shoe.”

(Actually, Noguchi kept the shoes in her bedroom, but not next to her pillow, Mimura said with a laugh by telephone, speaking through an interpreter from Asics’s headquarters in Kobe, Japan.)

Hall and Kastor said they planned to give the rice-husk shoes a thorough test drive to measure cushioning and stability. If they are not satisfied, they will run the Olympic marathon in more generic Asics models. Even under the best of circumstances, marathon runners face sore and swollen feet, blisters and the occasional wandering toenail. Nike and Adidas say they have their own grip technologies involving the use and placement of certain rubber compounds on the soles of shoes.

Image Mimura fitting a runner for shoes in Kobe, Japan. Credit... Ko Sasaki for The New York Times

“It’s kind of like when you’re dating a girl,” Hall said. “For some, it takes two days for them to know that’s the person they’re going to marry. For some, it takes four years. You’ve got to believe in your shoes. I’m as curious as everyone else about what makes this shoe so special.”