Shohei Ohtani was born on July 5, 1994, in Mizusawa (now part of Ōshū), Iwate, Japan, to Kayoko and Toru Ohtani. His mother Kayoko was a national-level badminton player in high school and his father Tōru (徹), who worked at a local automobile manufacturing plant, was an amateur baseball player who played in the Japanese Industrial League.
Ohtani is the youngest of three children. He has one older sister, Yuka, and one older brother, Ryuta (龍太), who is also an amateur baseball player in the Japanese Industrial League.
In Japan, Ohtani was known as a "yakyū shōnen" (野球少年; "baseball boy")—a kid who lives, eats and breathes baseball. Coached by his father, he displayed an aptitude for the game at an early age. He began playing baseball in his second year of elementary school, and as a seventh-grader, Ohtani recorded all but one of 18 outs in a six-inning regional championship game.