Yokawa started playing baseball in 2nd grade as a third baseman for the East Sekime Lions (little league), then he doubled as a pitcher and infielder in junior high.

[1] He was converted to a shortstop upon entering Konkōōsaka High School, and experienced playing in the Spring Koshien in his third year.

2015 He started training as an infielder with the main squad during spring camp, but dislocated his left shoulder when he made a diving catch during a friendly match with the Samsung Lions (KBO).

He played as a short stop or 2nd baseman in 17 games, batted an average of 0.345, and recorded 13 RBIs including 2 home runs.

[12] On April 29, his first career home run won the match against the Baystars, and he got to experience his first hero interview with pitcher and fellow 2013 draftee Yuta Iwasada.

[13] He then alternated as a 3rd baseman or left outfielder during his next appearances, though mostly as substitute for other starters, until he fell into a slump and was eventually sent back to the farm.

He finished the season in the farms and once again topped the league in RBIs with 91, and tied with Carp's Xavier Batista as the home run leader with 21.

[4] When his performance began to improve in 2017, his teammates in the farm noticed his habit of pounding his chest with his palms after he hits a home run, and promptly gave him the nickname "Gorilla".

By 2018, his teammates would do the "Gorilla Pose" ("Go-ri-ra Po-su" or ゴリラポーズ) after he hit one home run after another, both in the farm and main squad games.

[21] This eventually spread and even the main squad members now call him by this nickname, and greet him with this chest-slapping gesture as he returns to the dugout after a successful run.