Yuichiro Nagashima

Nagashima joined the team of Nippon Kempo and started training seriously when he was matriculated in University of Marketing and Distribution Sciences. In addition, Nagashima started participating professional mixed martial arts bouts. He also started cosplaying anime characters during his entrance to the ring.

Since 2007, Nagashima shifted his workplace to kickboxing, and he became known as "Otaku kickboxer" because of his entrance show before the bouts. He won ten consecutive victories, and won the vacant title of NJKF at Super welterweight on December 9, 2008. This was the first time for NJKF that the kickboxer who is not the member of NJKF wins the title of NJKF (Sakigake juku is not member of NJKF).

On January 25, 2009, he was chosen and awarded 2008 Outstanding Performance Award by NJKF, and also given 3 more awards certified combat sports medias.[3]

After winning the title, Nagashima was offered by K-1. He participated K-1 World MAX 2009 Japan Tournament on February 23, 2009, and he knocked out Hayato at 2R at the quarterfinal, but he was beaten by Yuya Yamamoto and lost by TKO because of being cut at the semifinal.

After the Japanese tournament, Nagashima was offered to fight against Albert Kraus from Netherlands on April 21. They engaged in a heated war of words before the bout where Kraus said "he seems to be a gay". The fight ended in Nagashima losing by knockout in round one. On October 26, Nagashima was offered to fight against Xu Yan from China. Although he trained at Masato's gym, he was knocked out at round one. In December, he was awarded the 2009 Walkout of the Year by Inside MMA of HDNet.[4]

On March 27, 2010, Nagashima participated to K-1 World Max 2010 Japan tournament. He won the tournament with 3 consecutive knock outs. Although he wanted to defend his NJKF title after this tournament, he returned his title as on 1 April because he was going to participate the world tournament and it was hard to arrange his schedule for defending title.[5]

On December 31, 2010, Nagashima took part in a "mixed rules" bout against judo and Brazilian jiu-jitsu expert Shinya Aoki at Dynamite!! 2010, the annual New Year's Eve fight festival. One round was to be held under kickboxing rules and the other under mixed martial arts rules. A coin toss decided that the kickboxing round was to commense first. Aoki took advantage of the fact that he only had to survive through a single three-minute round of kickboxing and thus threw pointless attacks like flying dropkicks and rolling heel kicks while holding onto the ring ropes in order to run the clock down. As the second round began, and Aoki now in his element under MMA rules, he dropped immediately for a double leg takedown, while Nagashima launched a flying knee square into Aoki's jaw. The blow instantly knocked out Aoki, after which Nagashima followed up with a number of hammerfists on the supine Aoki. The referee stepped in and stopped the fight four seconds into the period.[6]

He faced Henri van Opstal at REBELS 13 in Tokyo on October 28, 2012 with a place at the Shoot Boxing World Tournament 2012 on the line. He lost via unanimous decision (30-29, 30-29, 29-28).[7][8][9]

He lost a one-sided unanimous decision to Robin van Roosmalen at Glory 4: Tokyo - 2012 Heavyweight Grand Slam in Saitama, Japan on December 31, 2012 after being dropped in round one.[10][11][12]

He lost to Yoshihiro Sato by unanimous decision at Hoost Cup: Kings in Nagoya, Japan on June 16, 2013.[13][14][15][16]

Nagashima stopped a three-fight skid when he beat Hiroki Shishido by unanimous decision at Shoot Boxing Battle Summit Ground Zero Tokyo 2013 in Tokyo, Japan on November 15, 2013.[17][18]

On March 6, 2011, Nagashima appeared in the puroresu promotion Pro Wrestling ZERO1 to challenge fellow rookie Daichi Hashimoto, who was scheduled to face Masahiro Chono, and said that he had also made his debut in wrestling and soon would be Daichi's rival. Nagashima began training in the ZERO1 dojo under Shinjiro Otani, who was also Hashimoto's trainer. Although Daichi was the original target to Yuichiro, veteran wrestler Kohei Sato offered to wrestle Nagashima first, so Yuichiro had his debut on May 5 at the Korakuen Hall against him, with th Otaku Kickboxer winning the bout. The match was highly praised and some said that Yuichiro's skill was such that he seemed to have years of experience. Later, on June 14, Yuichiro had his first match against Daichi, teaming with former yokozuna and K-1 fighter Akebono to defeat Hashimoto & Otani. Two months after, Nagashima teamed up with Hashimoto and Otani to defeat Ryoji Sai, KAMIKAZE & Munenori Sawa.

After their last meeting, Nagashima announced his intention to face Masahiro Chono, who had wrestled against Hashimoto. Chono agreed and the match was held in Inoki Genome Federation, with Nagashima in the losing side. Thereafter, Yuichiro began competing actively for IGF, achieving significant victories over Munenori Sawa and Bob Sapp. Upon his return to ZERO1, Nagashima came in a feud with Fujita Hayato, being defeated by Fujita in a singles match. This was his final match of the year, as Nagashima returned to kickboxing shortly after.

In 2013, Nagashima made a return to pro wrestling in IGF, beating Black Tiger in two consecutive matches.

In February 2020, Nagashima made his debut in lethwei rules against Aut Chin Thwai, being defeated after a leg injury at the third round. He entered the match wearing the first anime cosplay he wore in his career, that of Haruhi Suzumiya from the eponymous franchise, and suggested this was his last fight.[19][20]

Nahashima was scheduled to face Shohei Asahara, Yasuomi Soda and Yusaku Nakamura in his retirement exhibition match at DEEP☆KICK 55 on September 23, 2021.[21] As in the previous occasion, he came to the match wearing a significant cosplay, the same Miku Hatsune costume he wore in his K-1 championship in November 2008, and thanked the fans for their support in his 14 years career.[2]