Seven-a-side Rugby Tournaments

There are various stories about when the first seven-a-side rugby (rugby sevens) tournament was held in Japan. It has generally been considered to be 29 April 1930 which is described in various related books including “The History of Japanese Rugby” and “The 100-Year History of Keio University”. Chronologies, which are contained in “The History of Rugby at Aoyama Gakuin University” and “The History of Rugby at Hitotsubashi University”, also follow this date.
“The History of Japanese Rugby” tells that the date of the first tournament was held on 29 April 1930, as follows:
“On 29 April 1930, the seven-a-side rugby tournaments were held at the Imperial University Komaba Sports Ground sponsored by the Japan East Rugby Football Union. In these tournaments, participating teams were divided into three classes, the university and Old Boy (OB) class, the college class, the junior-high school class, and the company class. These tournaments were held in March or April when all events scheduled in the year were completed, while achieving less attention. However, almost all the famous rugby teams participated.”
“Sports Yearbook Vol. 15: 1930” (edited by Asahi Shimbun) describes as follows: “Seven-a-side Rugby: The very first tournaments of seven-a-side rugby were held in Japan at the sports ground of the Tokyo Imperial University on 7 February 1930. The Tokyo Railway Bureau team became the champion by defeating the Ministry of Railways 9-3. In a seven-a-side rugby game, seven players formed one team consisting of three FWs, one HB, two TBs, and one FB. The total length of a game reached 16 minutes, 7 minutes for the first half and then the second half each, with 2-minute half time.” This shows us that seven-a-side tournaments had already been held even prior to April 29.
 “Study of the History of Rugby at Waseda” refers to other seven-a-side matches as follows: On 3 April 1930, the 1st Seven-a-Side Rugby Championship sponsored by graduate ruggers and supported by the Ministry of Education, Science, Sports and Culture - College class: Seikei 21 - 0 Mito; Undergraduate class: Engineering Dept. of Kyoto Univ. 11 - 5 Economics Dept. of Kyoto Univ.“ 29 April 1930: the 1st Seven-a-Side Rugby Championships sponsored by the Japan East Rugby Football Union - Junior-high school class: Aogaku Junior-High School 9 - 3 Keio Junior-High School; Keio A 9 - 6 Meiji A; Company class: Mitsubishi Club 23 - 0 Tokyo Denki.”
The morning Asahi Shimbun paper dated 28 April 1930 reported about the first-day results of the seven-a-side rugby tournaments. The 30 April morning paper ran the following article on one of its pages: “Seven-a-side Rugby Tournaments Held at Komaba Yesterday - The second day of the Seven-a-Side Rugby Tournaments, sponsored by the Japan East Rugby Football Union, was held at the Komaba Sports Ground on the 29th from 9:20 AM. Mitsubishi club, Aogaku Junior High School, and Keio A became the champions respectively, being awarded the champion plaques.”