Born and raised in the Nishinari-ku district Osaka, Japan, Kunimoto was a professional skateboarder from the age of 17 until he was 24, when he began training in mixed martial arts.

However, Kunimoto would go on to compile a record of 14-5-2 with one no contest and captured the HEAT Welterweight Championship, subsequently defending his title twice, before being signed by the UFC.

[10] However, Kunimoto pulled out of the fight in late August citing injury and was replaced by returning veteran Keita Nakamura.

He made his against Satoru Kitaoka on December 29, 2017, at RIZIN World Grand Prix 2017: 2nd Round in a 75kg catchweight bout.

[17] In his promotional debut, Kunimoto faced Ed Ruth at Bellator 224 on July 12, 2019 and lost the fight via TKO in the second round.

[25] On April 1, 2023 at Rizin 41 – Osaka, Kunimoto lost to Keita Nakamura via second round TKO stoppage after being dropped with a right straight and getting finished with a soccer kick.