Otsuka made his professional MMA debut in October 2006 and lost the bout via submission in the second round.
[5] Otsuka made his first title defense attempt against Yoshiro Maeda at Deep 57: Impact on February 18, 2012.
In July 2017, Otsuka made his debut for Rizin Fighting Federation.
[8] Otsuka faced Hiroki Yamashita in the opening round of the Bantamweight Grand Prix at Rizin 29 on May 30, 2021.
[10] Otsuka was scheduled to face Hiromasa Ougikubo in the quarterfinals on September 19, 2021 at Rizin 30.