Hirasawa teamed up with Ryusuke Taguchi to participate in his first tournament, the National Area Tag League 2006 where they were placed in block C and lost both of their matches.

Hirasawa would make several appearances for Pro Wrestling Zero1, the most notable of which was when he and Manabu Nakanishi participated in the Passion Cup Tag Tournament 2008.

The pair participated in the 2008 G1 Tag League block B, they would only gain a single point when they drew with Manabu Nakanishi and Yutaka Yoshie.

At Wrestle Kingdom IV in Tokyo Dome, Hirasawa, along with Inoue and Super Strong Machine defeated Jyushin Thunder Liger, Koji Kanemoto, and Kazuchika Okada in the opening match.

On 13 May in Rahway, New Jersey, he entered the tournament to determine the first ever IWGP Intercontinental Champion, losing to Yujiro Takahashi in his first round match.

[8] 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.

[12] 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.

[16] 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.

[21][22] 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.

[26] The following month, Bone Soldier entered the 2016 World Tag League, teaming with Bullet Club stablemate Bad Luck Fale.