To be considered a Young Lion one must have trained through the NJPW system.
Currently, there are two schools where an individual can train to become a Young Lion: the NJPW Dojo in Japan and its American counterpart the NJPW Dojo in Los Angeles, USA.
Young Lions live in dormitories adjacent to their dojo and are expected to perform household duties such as cleaning, laundry, and cooking. Before wrestling shows a Young Lion is also expected to carry the baggage of their seniors, assemble the ring, and arrange guest seating. They are also responsible for the security of the audience, shielding them from brawls which may spill outside the ring. Shinsuke Nakamura and David Finlay are the only two wrestlers in history to win a championship title during their Young Lion days.
The Young Lion Cup
In the past, the Young Lions had their own tournament dubbed the Young Lion Cup - a successor to the Karl Gotch Cup promoted by the NJPW in the 1970s. The Young Lion Cup was held to determine the top Young Lion of the promotion.
For some wrestlers like Masahiro Chono, Manabu Nakanishi, Satoshi Kojima and Hiroshi Tanahashi it was their first taste of success. Later in their careers, they would go on to win the G1 Climax and the IWGP Heavyweight Championships respectively.
The Young Lion Cup went on hiatus in 2005 with no word on its return until 2017 when Yuji Nagata proposed a revival of the tournament. On September 26 of the same year, NJPW officially announced its return, and Katsuya Kitamura was crowned the first Young Lion Cup Champion in 12 years on December 21, 2017.
Lions Gate Project
The Young Lions in Japan have their own show called the Lions Gate Project where they face off against veteran wrestlers and rookies from other promotions in Japan. Young Lion matches mainly consist of basic moves such as entrance with full power running, elbows, body slams, and dropkicks. At the end of a match, it is customary for a Young Lion to finish with the Boston Crab or an original technique.
Lions Break Project
The Young Lions in the United States have their own show called the Lions Break Project which is the counterpart of Lion's Gate Project shows in Japan, where they also face off against veteran wrestlers and independent wrestlers from the United States.
The list of trainers who train the Young Lions during their early days.
Young Lions typically wear black fitted shorts and ring shoes. This uniform is commonly seen as a symbol of strong style. Even a seemingly benign addition to their attire like a knee pad can leave an impression; implying that the rookie is well on his way to success.  As a rookie advances and gains the respect of his peers and the audience, he may be awarded more accessories such as kick pads. 
However, some wrestlers like Katsuyori Shibata choose to keep their black shorts and ring shoes even after they become part of the main roster.
The Learning Excursion
Typically three years after their Young Lion debut students are sent abroad to continue their training. This is often referred to as a "Learning Excursion". There are currently 3 NJPW training meccas in the world where a Young Lion might be sent: the USA, Mexico, and Europe.
After this special training is complete and a Young Lion returns home to the NJPW in Japan they graduate and are no longer considered a Young Lion.
List of current Young Lions
The following is a list that contains the current wrestler in their Young Lion status.
|Hirai Kawato||January 1, 2016||Japan dojo||On a learning excursion in Mexico|
|Hikuleo||November 12, 2016||Japan Dojo||On a learning excursion in the United Kingdom|
|Tomoyuki Oka||January 1, 2017||Japan Dojo||On a learning excursion in the United Kingdom|
|Shota Umino||April 13, 2017||Japan Dojo||On a learning excursion in the United Kingdom|
|Ren Narita||July 4, 2017||L.A. Dojo||On a learning excursion in the United States|
|Yota Tsuji||April 10, 2018||Japan Dojo|
|Yuya Uemura||April 10, 2018||Japan Dojo|
|Clark Connors||September 30, 2018||L.A. Dojo|
|Alex Coughlin||September 30, 2018||L.A. Dojo|
|Gabriel Kidd||July 21, 2013||L.A.Dojo|
|Karl Fredericks||November 10, 2018||L.A. Dojo||On a learning excursion in the United States|
List of Graduates
The following is a list of Japanese and gaijin wrestlers who have graduated from the NJPW Dojo in Japan, along with the USA Dojo in Long Beach, California.
|Yoshiaki Fujiwara||November 12, 1972||Active in Japan|
|Gran Hamada||March 16, 1972||Active in Japan|
|Mr. Pogo||March 20, 1972||Died on June 23, 2017|
|Ryuma Go||September 9, 1972||Died on October 18, 2009|
|Don Arakawa||September 19, 1972||Died on November 5, 2017|
|Kuniaki Kobayashi||February 1, 1973||Active in New Japan Pro Wrestling|
|Killer Khan||1973||Retired on 1987|
|Satoru Sayama||May 28, 1976||Active in Real Japan Pro Wrestling|
|Akira Maeda||August 25, 1978||Owner of Fighting Network RINGS|
|Hiro Saito||August 26, 1978||Active in New Japan Pro Wrestling|
|Shunji Kosugi||Febuary 1981||Retired on April 10, 1988|
|Nobuhiko Takada||1981||President of Rizin Fighting Federation|
|Kazuo Yamazaki||May 6, 1982||Active in New Japan Pro Wrestling|
|Tatsutoshi Goto||December 2, 1982||Semi Active in Japan|
|Jushin Thunder Liger||March 3, 1984||Retired|
|AKIRA||October 12, 1984||Active in Wrestle-1|
|Shinya Hashimoto||September 1, 1984||Died on July 11, 2005|
|Keiji Mutoh||October 5, 1984||Owner of Wrestle-1|
|Takuma Sano||March 3, 1984||Active in Japan|
|Yoji Anjo||July 8, 1985||Retired on March 19, 2015|
|Kenichi Oya||April 20, 1986||Active in Cho Sento Puroresu FMW|
|El Samurai||July 24, 1986||Semi Active in Japan|
|Hiroshi Hase||February 28, 1986||Retired on August 27, 2006|
|Takashi Iizuka||November 2, 1986||Retired on February 21, 2019|
|Ultimo Dragon||May 13, 1987||Active in Dragon Gate|
|Michiyoshi Ohara||June 30, 1990||Retired in 2008|
|Koji Kanemoto||November 7, 1990||Active in Japan|
|Hiroyoshi Tenzan||January 11, 1991||Active in New Japan Pro Wrestling|
|Satoshi Kojima||July 16, 1991||Active in New Japan Pro Wrestling|
|Osamu Nishimura||April 21, 1991||Active in All Japan Pro Wrestling|
|Shinjiro Otani||June 25, 1992||Active in Pro Wrestling Zero1|
|Tatsuhito Takaiwa||July 21, 1992||Active in Pro Wrestling Zero1|
|Yuji Nagata||September 14, 1992||Active in New Japan Pro Wrestling|
|Kendo Kashin||September 21, 1992||Active in Japan|
|Manabu Nakanishi||October 13, 1992||Active in New Japan Pro Wrestling|
|Yutaka Yoshie||December 9, 1994||Active in All Japan Pro Wrestling|
|Tadao Yasuda||February 1994||Retired on February 4, 2011|
|Kazuyuki Fujita||November 1, 1996||Semi Active in Japan|
|Togi Makabe||February 15, 1997||Active in New Japan Pro Wrestling|
|Hiroshi Tanahashi||October 10, 1999||Active in New Japan Pro Wrestling|
|Katsuyori Shibata||October 10, 1999||Active in New Japan Pro Wrestling|
|Wataru Inoue||October 10, 1999||Retired on March 3, 2013|
|KENSO||January 4, 2000||Active in Japan|
|Shinsuke Nakamura||August 29, 2002||Active in World Wrestling Entertainment|
|Yoshitatsu||October 12, 2002||Active in All Japan Pro Wrestling|
|Ryusuke Taguchi||November 22, 2002||Active in New Japan Pro Wrestling|
|Hirooki Goto||July 6, 2003||Active in New Japan Pro Wrestling|
|Finn Bálor||April 2006||Active in World Wrestling Entertainment||Graduated from NJPW USA Dojo|
|Yujiro Takahashi||July 26, 2004||Active in New Japan Pro Wrestling|
|Tetsuya Naito||May 27, 2006||Active in New Japan Pro Wrestling|
|Taichi||December 2, 2002||Active in New Japan Pro Wrestling|
|Mitsuhide Hirasawa||January 28, 2006||Inactive|
|Yoshi-Hashi||July 6, 2008||Active in New Japan Pro Wrestling|
|Kazuchika Okada||August 29, 2004||Active in New Japan Pro Wrestling|
|Tama Tonga||2008||Active in New Japan Pro Wrestling|
|Bad Luck Fale||April 4, 2010||Active in New Japan Pro Wrestling|
|El Desperado||March 7, 2010||Active in New Japan Pro Wrestling|
|EVIL||May 13, 2011||Active in New Japan Pro Wrestling|
|David Finlay||December 22, 2012||Active in New Japan Pro Wrestling|
|Hiromu Takahashi||August 24, 2010||Active in New Japan Pro Wrestling|
|Juice Robinson||September 4, 2015||Active in New Japan Pro Wrestling|
|Sho||November 15, 2012||Active in New Japan Pro Wrestling|
|Yoh||November 19, 2012||Active in New Japan Pro Wrestling|
|Jay White||January 30, 2015||Active in New Japan Pro Wrestling|
|Toa Henare||September 1, 2016||Active in New Japan Pro Wrestling|
The following is a list of notable wrestlers who have trained at the NJPW Dojo but did not officially graduate.
|Masakatsu Funaki||March 3, 1985||Active in Japan||Funaki would leave NJPW in 1988 and later graduated in the UWF Dojo.|
|Minoru Suzuki||June 23, 1988||Active in New Japan Pro Wrestling||Suzuki would leave NJPW in 1989 and later graduated in the UWF Dojo.|
|Akira Katayama||January 25, 1987||Retired on January 8, 1992|
|Poison Sawada Julie||1981||Retired on November 25, 2012||Sawada would leave NJPW in 1983 due to injury and later returned to wrestling in 1988 and later wrestled in DDT Pro-Wrestling and retired there.|
|Masakazu Fukuda||March 20, 1996||Died on April 19, 2000|
|Katsushi Takemura||July 22, 1997||Retired on January 6, 2009|
|Akiya Anzawa||September 21, 2003||Retired on January 8, 2006|
|Hiroshi Nagao||February 2, 2003||Retired on October 26, 2008|
|Taiji Ishimori||2004||Active in New Japan Pro Wrestling|
|Takumi Honjo||February 25, 2016||Retired||Retired, after leaving the NJPW Dojo.|
|Katsuya Kitamura||March 13, 2017||Inactive||Winner of the 2017 Young Lion Cup, Four months later he left NJPW due to injury.|
|Tetsuhiro Yagi||May 9, 2017||Retired||Retired, after leaving the NJPW Dojo due to personal issues.|
|Teruaki Kanemitsu||January 1, 2016||Inactive||He left NJPW in April 2019 after being injured.|