Mishima is known for his charisma and emphasis on entertainment as well as competition. He typically enters the arena in an outlandish fashion, such as in his UFC debut, where he sported a bathrobe and devil mask while clutching a Snoopy stuffed animal.
On 2005-02-12, Mishima was victorious against fellow DEEP veteran Tomomi Iwama becoming the first lightweight (155 lbs.) champion of the organisation. However, Mishima didn't defend his belt and returned it one year later.
Mishima has had four fights in PRIDE, winning over Charles Bennett and Marcus Aurelio and losing to Yves Edwards and Ralph Gracie. His most recent appearance was in the reserve fight of PRIDE Bushido 9 on 2005-09-25, where he defeated fellow alternate Charles Bennett with an ankle lock.
On 2006-11-18, Mishima made his debut in the U.S. at UFC 65. Joe Stevenson, the winner of The Ultimate Fighter 2 who had just moved down to the lightweight division (155 lbs.), defeated Mishima in the first round by a guillotine choke.
Mishima's fought Kenny Florian at UFC Fight Night 9 on April 5, 2007 in Las Vegas. Mishima lost to a rear naked choke, shortly after attempting to submit Florian with a knee bar.
On 2008-05-19 Mishima dropped to featherweight (145 lbs.) to fight Masakazu Imanari. Mishima won by unanimous decision, becoming DEEP featherweight champion. He also became the first man to capture the DEEP belt in two different divisions.
| Result | Record | Opponent | Method | Event | Date | Round | Time | Location |
|---|---|---|---|---|---|---|---|---|
| Win | 18-6-2 | Masakazu Imanari | Decision (Unanimous) | DEEP - 35th Impact | 3 | 5:00 | Tokyo, Japan | |
| Loss | 17-6-2 | Kenny Florian | Submission (Rear Naked Choke) | UFC - Fight Night 9 | 3 | 3:57 | Nevada, United States | |
| Loss | 17-5-2 | Joe Stevenson | Submission (Guillotine Choke) | UFC 65 - Bad Intentions | 1 | 2:07 | California, United States | |
| Win | 17-4-2 | Charles Bennett | Submission (Ankle Lock) | PRIDE - Bushido 9 | 1 | 4:04 | Tokyo, Japan | |
| Loss | 16-4-2 | Yves Edwards | Submission (Armbar) | PRIDE - Bushido 7 | 1 | 4:36 | Tokyo, Japan | |
| Win | 16-3-2 | Tomomi Iwama | Decision (Unanimous) | DEEP - 18th Impact | 3 | 5:00 | Tokyo, Japan | |
| Win | 15-3-2 | Marcus Aurelio | Decision (Split) | PRIDE - Bushido 4 | 2 | 5:00 | Nagoya, Japan | |
| Win | 14-3-2 | Robert Emerson | Decision (Unanimous) | DEEP - 14th Impact | 3 | 5:00 | Osaka, Japan | |
| Loss | 13-3-2 | Ralph Gracie | Decision (Unanimous) | PRIDE - Bushido 1 | 2 | 5:00 | Saitama, Japan | |
| Win | 13-2-2 | Tetsuji Kato | Decision (Majority) | DEEP - 12th Impact | 3 | 5:00 | Tokyo, Japan | |
| Win | 12-2-2 | Masakazu Imanari | TKO (Punches) | DEEP - 11th Impact | 2 | 2:58 | Osaka, Japan | |
| Win | 11-2-2 | Fabio Mello | Decision (Unanimous) | DEEP - 8th Impact | 3 | 5:00 | Tokyo, Japan | |
| Loss | 10-2-2 | Takanori Gomi | TKO (Punches) | Shooto - 2002 Year-End Show | 2 | 0:52 | Tokyo, Japan | |
| Win | 10-1-2 | Takafumi Ito | Submission (Armbar) | DEEP - 6th Impact | 1 | 0:53 | Tokyo, Japan | |
| Win | 9-1-2 | Iran Mascarenhas | Submission (Achilles Lock) | Shooto - Treasure Hunt 7 | 2 | 4:53 | Osaka, Japan | |
| Win | 8-1-2 | Ben Thomas | TKO (Punches) | Shooto - Treasure Hunt 3 | 1 | 3:07 | Kobe, Japan | |
| Win | 7-1-2 | Ryan Bow | Decision (Majority) | Shooto - To The Top Final Act | 3 | 5:00 | Tokyo, Japan | |
| Win | 6-1-2 | Marcio Barbosa | Submission (Kneebar) | Shooto - R.E.A.D. Final | 2 | 4:51 | Tokyo, Japan | |
| Win | 5-1-2 | Tony DeDolph | Submission (Armbar) | HOOKnSHOOT - Fusion | 1 | 4:53 | Indiana, United States | |
| Draw | 4-1-2 | Marcio Feitosa | Draw | Shooto - R.E.A.D. 9 | 3 | 5:00 | Yokohama, Japan | |
| Win | 4-1-1 | Justin Wisniewski | Submission (Cobra Hold) | Shooto - R.E.A.D. 8 | 1 | 1:30 | Osaka, Japan | |
| Loss | 3-1-1 | Din Thomas | TKO (Cut) | Shooto - R.E.A.D. 2 | 2 | 3:37 | Tokyo, Japan | |
| Win | 3-0-1 | Kazuya Abe | Decision (Unanimous) | Shooto - Renaxis 5 | 2 | 5:00 | Osaka, Japan | |
| Win | 2-0-1 | Makoto Ishikawa | Decision (Unanimous) | Shooto - Renaxis 3 | 2 | 5:00 | Tokyo, Japan | |
| Win | 1-0-1 | Hiroki Kotani | Submission (Rear Naked Choke) | Shooto - Shooter's Passion | 1 | 4:00 | Tokyo, Japan | |
| Draw | 0-0-1 | Satoshi Fujisaki | Draw | Shooto - Las Grandes Viajes 1 | 2 | 5:00 | Tokyo, Japan | |