Yamakita became interested in mixed martial arts while watching Pride Fighting Championships as a child and began wrestling in the fourth grade of elementary school.
He continued wrestling while attending the Inabe Sogo Gakuen High School and Senshu University.
Yamakita made his mixed martial arts debut while working at a restaurant, but soon quit his job in the food industry to take up a position as a coach at the Toikatu Dojo.
[6] Yamakita faced the debuting Tomoki Otsuka at Pancrase 319 on October 25, 2020, in the penultimate bout of the tournament.
Yamakita advanced to the tournament final, held at Pancrase 320 on December 13, 2020, where he faced the undefeated Taiga Tanimura.
[10] He won the fight by a first-round submission, forcing Ozaki to tap with an armbar near the very end of the round.