Yukihiro Shimura always arrives first. He quietly puts on his baseball uniform. He rakes the dirt field meditatively. He picks up the coconut husks and dog poop. And, finally, when he finishes, he bows to Rio de Janeiro’s only baseball field.

Then his misfit team — including a geologist, graphic designer, English teacher, film student, voice actor and motorcycle delivery man — starts to form. Most are in their 20s and 30s, and some are still learning the basics of throwing, catching and swinging a bat.

It was not what Mr. Shimura envisioned when he signed up for this gig. “In my mind, the age range would be 15 to 18,” he said. “I should have asked.”

For the past two decades, Mr. Shimura, 53, was one of Japan’s top high-school baseball coaches. Now he is more than 10,000 miles from home, on a two-year mission from the Japanese government to spread the gospel of baseball.

The challenge is that Japan sent him to the land of soccer.

Despite being the largest nation in Latin America — the region that has fueled baseball’s growth in recent decades — Brazil is baffled by the sport. Brazilians say that compared with their national pastime, baseball has too many rules, too much equipment and too much standing around.