New Japan Pro-Wrestling (1999–2004) Murakami entered
professional wrestling in 1998 when he joined
Antonio Inoki's Universal Fighting-Arts Organization alongside fellow judoka
Naoya Ogawa. They were sent to
New Japan Pro-Wrestling, where Murakami initially gained fame for attacking wrestlers while sporting a white mask, becoming known as "The Terrorist of Heisei". During his early career, Murakami split his time between NJPW and shoot-style promotion
Battlarts to hone his skills as a wrestler. One of his first matches was at
Wrestling World 2000, teaming with Ogawa in a losing effort to
Shinya Hashimoto and
Takashi Iizuka when he submitted to Iizuka. On April 7, Murakami took on Iizuka in an attempt to avenge his loss but he once again fell to Iizuka by submission. In early 2001, Murakami would also wrestle several times for the newborn
Pro Wrestling ZERO1, main eventing the promotion's second ever show where he and Ogawa lost to
Mitsuharu Misawa and
Takeshi Rikio. Murakami became known for his wild, seemingly uncontrollable style of wrestling, predominately made up of punches, kicks, and legitimate judo/MMA throws and submissions, with very little actual wrestling moves in his moveset. In August 2001, Murakami entered the 2001
G1 Climax, his first time ever competing in the tournament. He finished fourth in his block with 5 points scoring victories over Nakanishi and
Tadao Yasuda while going to a double countout with eventual winner, Yuji Nagata. In early 2002, Murakami joined NJPW full time, and in the summer, Murakami joined the
heel stable
Makai Club, where he was considered one of the highest-ranking members behind only
Tadao Yasuda. On December 10, 2002, Murakami challenged Yuji Nagata for the
IWGP Heavyweight Championship. Despite making Nagata bleed and trapping him in his own finishing move, the Nagata Lock II, Murakami was defeated by Nagata. At
Wrestling World 2003, Murakami and Yasuda lost to
Michiyoshi Ohara and
Shinsuke Nakamura. However, an injury to Steele would give the title shot to Murakami and Yasuda who unsuccessfully challenged
Cho-Ten on February 16. In the fall of 2003, Murakami began competing in a series of three "bounty" matches, where the winner would receive a cash prize from Makai Club leader
Kantaro Hoshino. He defeated
Shinya Makabe at Road to Ultimate Crush on September 21 in a 1,000,000 Yen Bounty match, then fellow Makai Club member
Katsuyori Shibata at Ultimate Crush II on October 13 in a 2,000,000 Yen Bounty match, and finally
Koji Kanemoto at Yokohama Dead Out on November 3 in a 4,000,000 Bounty match. In early 2004, Murakami began feuding with
Hiroshi Tanahashi for the
IWGP U-30 Openweight Championship, which eventually led to an empty arena steel cage match on March 28 at King of Sports, won by Tanahashi. On May 3, 2004, at Nexxess in the
Tokyo Dome, Murakami teamed with
Masahiro Chono to unsuccessfully challenge
Yoshihiro Takayama and
Minoru Suzuki for the IWGP Tag Team Championship. Makai Club broke up in the summer of 2004 and Murakami would briefly join
Masahiro Chono's
Black New Japan stable before leaving New Japan shortly after. His last match under contract to the promotion took place on July 7, where he, Katsuyori Shibata,
Super Strong Machine,
Mitsuya Nagai and Masahiro Chono defeated Hiroyoshi Tenzan,
Osamu Nishimura, Shinya Makabe, Yuji Nagata and
Yutaka Yoshie. Murakami would return to New Japan for a one-off match at the
2006 Tokyo Dome show, losing to Yuji Nagata.
Big Mouth Loud (2005–2006) Having both left New Japan, Murakami and
Katsuyori Shibata announced the formation of a new promotion, Big Mouth Loud in January 2005. Backed by Fumihiko Uwai, the promotion was set to focus largely on shoot-style, and would use talent from other promotions as well as their own contracted wrestlers. At Big Mouth Loud's first show in September 2005, Murakami defeated Shibata in the main event. Murakami reignited his feud with
Enson Inoue at the next show in December 2005, defeating him in a singles match. Murakami continued to compete for BML until the promotion's closure in mid-2006.
Freelance (2006–2007) After Big Mouth Loud folded, Murakami went freelance and began working for
Pro Wrestling Zero1 in the summer of 2006. Murakami took part in ZERO1's 2006 Fire Festival tournament, making it to the semi-finals before losing to
Shinjiro Otani. In the first match of the 2007 Fire Festival, Murakami suffered a severe brain injury against Shinjiro Otani, which forced him to leave professional wrestling effective immediately to undergo brain surgery.
Return (2010–2014) In February 2010 Murakami returned to pro wrestling, as
Big Murakami, losing to Kensuke Sasaki in a match for Sasaki's
Kensuke Office promotion. He also returned to
Pro Wrestling Noah, and on March 26 teamed with Katsumi Usuda to challenge
Takeshi Rikio and Muhammad Yone for the GHC Tag Team Titles but they came up short. Murakami later announced Kensuke Office as his home promotion, and continued to compete with the promotion until its closure in 2014.
Return in Noah (2020–) On December 26 at Kongoh Produce ~ Diamond 3 Murakami made his return in
Pro Wrestling Noah as
NOSAWA Rongai announced his return to the company. On December 29 at
Takashi Sugiura 20th Anniversary Show he fought in a 7 vs 7 match and his team,
Takashi Sugiura,
Kazushi Sakuraba,
Kendo Kashin,
NOSAWA Rongai,
Kaz Hayashi,
Daisuke Nakamura won by defeating the whole
Kongoh led by
Kenoh. On January 4, 2021, at Noah New Sunrise 2021 Sugiura-gun (Kazunari Murakami,
Kazushi Sakuraba &
Takashi Sugiura) defeat Kongoh (
Katsuhiko Nakajima,
Kenou &
Masa Kitamiya) by referee's decision. On January 16, 2021, at Noah Higher Ground 2021 - Day 2 in another six-men tag team match Sugiura-gun (
NOSAWA Rongai &
Takashi Sugiura & Kazunari Murakami) defeat Kongo (
Kenou,
Manabu Soya &
Tadasuke). By defeating three times in a row the Kongoh stable Murakami earned a title match against
Kenou for the GHC National Title. On January 23, 2021, at the Noah Higher Ground 2021 - Day 3 show held at the
EDION Arena Osaka Kenou retained the title. ==Mixed martial arts record==