New Japan Pro-Wrestling (2006–2010) Hirasawa originally debuted for
New Japan Pro-Wrestling (NJPW) on 28 January 2006, losing to his mentor Takashi Iizuka. On 25 September, Saito would win his first championship when he won a battle royal for the vacant
WWC Caribbean Heavyweight Championship and would lose it on 27 November. On 19 February, he also won the
WWC Puerto Rico Heavyweight Championship and lost it on 26 March.
Return to NJPW and departure (2011–2017) Hirasawa returned to New Japan on 18 June, now going permanently by the Saito name, and turned on Seigigun and its leader Yuji Nagata, joining
Chaos. In August, Saito took part in the
2011 G1 Climax, losing his first eight matches only to pick up his opening win on the final day of the tournament in a match against former mentor, Yuji Nagata. On 19 September, Nagata defeated his former protégé in a grudge match. Saito's erratic behaviour and poor match results eventually led to the rest of Chaos kicking him out of the stable on 4 December 2011. After his exile from Chaos, Saito developed an alter-ego called "Captain New Japan", dressed in a variation of the
Captain America costume, complete with a shield. In November, Captain New Japan took part in the
2012 World Tag League, teaming with
IWGP Heavyweight Champion Hiroshi Tanahashi under the team name "Captain Ace". The team lost all six of their matches with Captain New Japan being pinned in each match. On 3 March 2013, Captain New Japan returned to Seigigun in an eight-man tag team match, where he, Nagata, Super Strong Machine and Wataru Inoue were defeated by
Hirooki Goto,
Karl Anderson,
Ryusuke Taguchi and
Tama Tonga. On 7 April, Captain New Japan was attacked by
Bad Luck Fale and
Prince Devitt and would also be unmasked by Devitt, however, his face was never shown. In response to this, Captain New Japan teamed up with Taguchi, Devitt's former
Apollo 55 partner, and challenged the two at
Wrestling Dontaku 2013, where they lost. Following these events, Captain New Japan fought against the newly formed
Bullet Club headed by Devitt and reformed his alliance with Tanahashi. On 4 August, Captain New Japan carried Tanahashi to the ring akin to Fale and Devitt and became involved in the match-up trying to limit the effects of Fale's interference; however, Devitt would ultimately defeat Tanahashi. In November, Captain Ace reunited for the
2013 World Tag League. Much like the previous year, the team lost their first five matches, but on the final day, they finally picked up a win over Fale and Devitt, with Captain pinning Devitt, costing the Bullet Club team a spot in the semifinals. On 13 April 2014, during NJPW's trip to
Taiwan, Hirasawa, working as Captain Taiwan, received his first title shot in the promotion, when he and Hirooki Goto unsuccessfully challenged Bullet Club representatives
Doc Gallows and Karl Anderson for the
IWGP Tag Team Championship. In early 2016, Captain New Japan became part of
Yoshitatsu's new anti-Bullet Club stable, Hunter Club. On 12 September, Yoshitatsu, upset with Captain New Japan's poor performances, announced a
Twitter poll that would decide whether he would get to stay in Hunter Club. On 25 September at
Destruction in Kobe, upon being denied a spot in Hunter Club, Captain New Japan turned on Yoshitatsu and defected to Bullet Club. The following day, Hirasawa was given the new ring name "Bone Soldier". He made his debut under the name on 8 October. The following month, Bone Soldier entered the
2016 World Tag League, teaming with Bullet Club stablemate Bad Luck Fale. The two lost all seven of their matches in the tournament, with Bone Soldier being pinned by his rival Yoshitatsu in their final match on 8 December. On 1 March 2017, Hirasawa's profile was removed from NJPW's website, confirming his departure from the company. ==Championships and accomplishments==