[1] Ogawa is also known for his career in professional wrestling, where he primarily worked for New Japan Pro-Wrestling (NJPW), and took part in one of the promotion's most high-profile feuds of the 1990s with Shinya Hashimoto.

[10] Ogawa runs a judo school in Chigasaki, Kanagawa Prefecture, Japan, where he trains potential Olympians and Paralympians in his network of dojos.

Ogawa made his debut in NJPW on April 12, 1997 at the Tokyo Dome, replacing the stipulated Ken Shamrock as the opponent for Shinya Hashimoto, then IWGP Heavyweight Championship titleholder.

In order to bounce back from the defeat, he started a special training, and ditched his trusted judogi for black tights, boots and fingerless gloves.

Hashimoto followed him to the country and attacked him (kayfabe this time) in a press conference, challenging him to a title match in Japan with Tatsumi Fujinami as special referee.

Naoya toured through United States, retaining the title before Dan Severn, Doug Gilbert and Biggie Biggs, trading it with Steele in a three-way match that also involved Brian Anthony on September 25, 1999, and finally coming back to Japan to meet Hashimoto.

His opponent carried out and performed a retirement ceremony, while Inoki and other tried to convince him not to do it; even Ogawa declared in a segment that he repented having finished off the career of his rival.

In 2001, after Shinya Hashimoto founded Pro Wrestling Zero-One, Ogawa left NJPW and moved in, forming a tag team with his former rival which was called "OH Gun".

In 2004, Ogawa took part in the foundation of the sports entertainment promotion Hustle, a combined effort between Zero-One and mixed martial arts league Pride Fighting Championships.

With Nobuhiko Takada acting on behalf of Sakakibara and Shinya Hashimoto backing Ogawa, it was decided they would prove their postures in an event where MMA fighters would face professional wrestling representatives.

Although his first match was a loss, being pinned by Matt Ghaffari with the help of several Monster Army members, he bounced back by summoning several high level wrestlers, among them Riki Choshu and Toshiaki Kawada, to help him and Hashimoto.

In September, after Ogawa lost to Fedor Emelianenko in 54 second at a Pride event, Takada started a mocking campaign against him and banned him from competing in Hustle for 54 days.

Deducting Captain O was really Ogawa, Takada's second-in-command Commander An Jo sent several Monster Army wrestlers to capture and tie him up, but O escaped by shedding this gimmick and adopting yet another, "Judo O", where he would wear a blue judogi along with his mask.

Ogawa had his first MMA fight the same year of his debut in NJPW, taking part in an event promoted by Chris Dolman in Holland in which he faced Rens Vrolijk.

Naoya evidenced his lack of MMA experience when he suffered heavy blows and almost failed his first morote gari, but he eventually took Goodridge down and gained dominant position as expected.

In 2002, Naoya participated in the first event of Universal Fighting-Arts Organization against another Olympic medalist, the Greco-Roman wrestling champion Matt Ghaffari, who had claimed he would knock Ogawa out with knee strikes.

After one minute and thirty seconds, the judoka landed a right punch that made Ghaffari stumble and fall, and the wrestler decided to tap out before receiving further damage.

His first opponent was K-1 veteran and MMA debutant Stefan Leko, whom Naoya shockingly knocked down with a punch before submitting him to an arm triangle choke.

Ogawa's last fight in mixed martial arts was at PRIDE Shockwave 2005 against the man who took from him the world judo championships the last time they fought, Hidehiko Yoshida.