TOKYO >> Kei Nishikori is the first Japanese man to reach a Grand Slam singles final, but in Japan he is seen as a most un-Japanese sports hero.

In 2004, as an eighth-grader with limited English abilities, he left his sleepy hometown, Matsue, on Japan’s rural backside to go to the United States to train at the IMG Academy in Bradenton, Florida, one of the world’s most competitive programs for grooming young tennis stars. Most of the handful of Japanese players who had studied there before him did not last long, but Nishikori thrived, staying until he turned pro in 2007.

Since then, Nishikori, 24, has become known for an aggressive style of play, with a leaping forehand shot that, while not uncommon among tennis players abroad, is so rare among his more earthbound Japanese peers that he has been given the nickname Air K.

To many in Japan, most unusual of all is that his parents, neither of whom played tennis as anything more than a hobby, gave Nishikori the freedom to pursue dreams that might have seemed outlandish.

In a country where youth sports programs are known for rigid conformity, Nishikori is revered as the superstar who dared from a young age to do things differently. Now, as Japan celebrates its newest sports hero, many tennis writers say the secret to Nishikori’s success is his unorthodox path.

"Kei Nishikori’s un-Japanese abilities and way of thinking are rooted in how he was raised," one widely read celebrity blog, Lifepages.jp, said last week.

Nishikori, who beat Novak Djokovic in the U.S. Open semifinals and will face Marin Cilic on Monday, has drawn special attention for his decision to leave Japan, where he was a rising star, at a time when there was much hand wringing about the declining number of Japanese youth showing the ambition to study abroad.

Two years before going to the U.S., while still a sixth-grader in Matsue, Nishikori swept three top age-group titles, including the All-Japan Junior Tennis Championships. But his father, Kiyoshi, said Japanese sports programs, with their rigid hierarchies and demands to conform, would not nurture a talent as unique as his son’s.

"Japanese tennis players have not had much success because their sense of individuality is weak when compared with players from overseas," Kiyoshi Nishikori was quoted as saying in the book "Fly, Kei Nishikori!"

Arriving in the United States, Kei Nishikori – who was 14 at the time, according to his website – entered IMG, which had become known as a star factory for producing players like Andre Agassi and Maria Sharapova.

There, Nishikori found himself in an alien world. He said later that it was a tough adjustment, but it also offered him a chance to get out of the glare of Japan’s sports media.

Nishikori’s father, an engineer, could not afford the hefty costs of sending his son to the United States to study tennis, according to Japan’s tennis blogs, but Nishikori was given a scholarship by Morita Tennis Fund, created by Masaaki Morita, a former executive at Sony and the younger brother of the company founder Akio Morita.

"I was worried at first because Kei was so shy," Morita said in an earlier interview published on the website ProTennis Game. "But surprisingly, he seemed better suited to life over there," he added, referring to the United States.

Most of those who get a scholarship stay in the United States for two years before returning to Japan. Nishikori was one of only two recipients who stayed for four years, according to Japanese tennis blogs.

Kiyoshi Nishikori gets much of the credit for laying the foundation for his son’s success.

Kei Nishikori’s love of tennis started at age 5, when his father brought back a children’s racket from a business trip to Hawaii. Nishikori took to the sport right away and was soon hitting balls against a wall at home with such ease that his parents enrolled him in a local tennis school at age 6.

The school’s coach, Masaki Kashiwai, said in a recent interview with the newspaper Nikkan Sports that he was impressed by the accuracy of Nishikori’s serve.

"He had ball control that only one player in 100 has and a knack for the game that only one in 100 has," Kashiwai said. "So together, he was a one in 10,000 player."

Kashiwai said that in elementary school, Nishikori frequently challenged and defeated older boys. His drive to succeed also impressed Dai Kawakami, the owner of a cram school in Matsue. Nishikori visited the school with his mother when he was 7 and told Kawakami that he wanted to study English so he could one day play tennis overseas, Kawakami said.

The boy’s determination led Kawakami to start a course for young children at his school, which until then had taught only high-school-level classes.

"Most children who want to be tennis players just play tennis," Kawakami said in a phone interview. "Kei was different. He knew he needed to study English."

Nishikori’s father spent weekends and holidays driving his son to a small tennis club not far from Kei’s grandparents’ home.

The club had just three courts, which are now called Court A, B and K – the last to honor Nishikori. One of the rackets Nishikori used as a student is now on display.

In a news program by the national broadcaster NHK, a staff worker at the club said Nishikori ran up and down a nearby flight of 41 stone steps to get in shape. He said Nishikori was tireless in his training.

Nishikori’s parents – his mother, Eri, is a piano teacher – have gotten credit from the Japanese news media for giving him the freedom to pursue his interests and not forcing him to spend his free time studying for junior high school and high school entrance exams.

Still, Nishikori told reporters at the U.S. Open on Saturday that while he also played baseball and soccer as a child, he was glad he could help tennis grow.

The United States "has a lot of respect for the sports," he said, "but not as much in Japan. I hope I can make a little bit difference."

Nishikori acknowledged that the time difference would make it difficult for his countrymen to watch the Open final. But, he added, he got plenty of messages after his semifinal victory, "even if it’s 4 a.m.," and said he hoped a lot of people would watch his match.

"I hope I can win and to make another history," he said.

© 2014 The New York Times Company