Yoshida was born in Yokohama, Kanagawa, Japan, where she taught herself how to throw the knuckleball at the age of 14 after watching Major League Baseball pitcher Tim Wakefield on television. She stands tall, and her pitches have been clocked at , while her knuckleball pitch velocity measures around 50 mph. As a high school sophomore at Kawasaki-kita Senior High School in Kawasaki, she threw the pitch well enough to earn a place on the school's baseball team. Her success caused a sensation in the national media, who dubbed her the Knuckle Princess. In 2008, she signed a contract to play for the of the Kansai Independent Baseball League.
