Even now, as one of Major League Baseball’s most prominent players, Shohei Ohtani is often described as an “eternal baseball kid.”
In many ways, that description fits. From the time he first picked up a bat in the second grade of elementary school to the present day, he seems to have been driven by a single desire: to give everything he has to the game he loves.

As a child, Ohtani was relatively tall but slender, and did not appear to possess exceptional power based on his build alone.
Yet by the third grade, he already had the strength to hit balls over the 70-meter fence installed in the outfield for Little League games.

According to Shoji Asari, the founder of the Mizusawa Little League, a third grader capable of clearing the fence was an extremely rare sight — perhaps one or two children nationwide.

There was a period afterward when Ohtani stopped hitting home runs, but by the sixth grade he hit ten in a season.
By his first year of middle school, he was even hitting balls out of a softball-only stadium.

Asari, who had watched Ohtani since he first joined the team, was stunned by his development.
“I’ve never seen a batter like this,” he recalled, later telling his wife at home, “Shohei can make it to the pros.”

From that early age, Ohtani continued to practice with a simple wish in mind:
to hit home runs, and to clear the fence that once stood in front of him.

Even now, having achieved those goals, he says he still plays baseball with the same feeling he had as a child.

Source

This quote comes from a Japanese book published in Japan and is not currently available in English.

Shohei Ohtani: Baseball Soaring Years II – MLB 2018–2024, Long Interview, p.108