Question: Who has been involved in more music groups, Ryuichi Kawamura or Billy Mackenzie?

full_context: Document 1: Takuya Kimura: Takuya Kimura (木村 拓哉 , Kimura Takuya , born November 13, 1972) , also known as Kimutaku, is a Japanese actor, singer, radio personality. He is regarded as a Japanese icon after achieving an unprecedented success as an actor and influencing Japanese culture, and established himself as one of the most successful celebrities in Asia.
Document 2: Ryuichi Kawamura: Ryuichi Kawamura (河村 隆一 , Kawamura Ryūichi , born May 20, 1970 in Yamato, Kanagawa) is a Japanese singer-songwriter, actor and record producer. He is best known as lead singer of the rock band Luna Sea. After the group disbanded in 2000, Kawamura continued his successful solo career. In 2005 he formed Tourbillon with fellow Luna Sea member Inoran and Hiroaki Hayama. He has recently rejoined Luna Sea, as they reunited in August 2010.
Document 3: Tourbillon (band): Tourbillon (トゥールビヨン , Tūrubiyon , French for "whirlwind") is a Japanese musical project formed in 2005 by Luna Sea members Ryuichi Kawamura (vocals) and Inoran (guitar), and D-Loop member Hiroaki "H. Hayama" Hayama (keyboards).
Document 4: Toshi (musician): Toshimitsu Deyama (出山利三 , Deyama Toshimitsu , born October 10, 1965 in Tateyama, Chiba) , known exclusively by his stage name Toshi, is a Japanese singer and songwriter. He is best known as the lead vocalist and a co-founder of the heavy metal band X Japan, which disbanded in 1997. Toshi then went on to have an extensive solo career. In 2007, X Japan reunited and began an ongoing world tour in 2010. His distinctive, impassioned tenor vocals have been compared to those of Steve Perry.
Document 5: Neil Mackie: Neil Mackie (born 1946) is a Scottish tenor. During his career as a singer, he was associated with the works of 20th-century composers, particularly Benjamin Britten, and Peter Maxwell Davies. He created the title role in Davies's opera "The Martyrdom of St Magnus" and Sandy in his "The Lighthouse" and performed in the world premieres of Davies's "Into the Labyrinth", cantata for tenor and chamber orchestra, and "The Jacobite Rising". He has also premiered vocal works by Elliott Carter ("In Sleep, in Thunder"), Hans Werner Henze ("Three Auden Songs") and songs by Benjamin Britten.
Document 6: Billy MacKenzie (motorcyclist): Billy MacKenzie (born 7 April 1984 in Edinburgh) is a Scottish professional motocross racer.
Document 7: Alan Rankine: Alan Rankine (born 17 May 1958) is a Scottish musician and record producer best known as keyboardist/guitarist for the rock band Associates, which he co-founded with Billy Mackenzie in the late 1970s.
Document 8: Toru Yamashita: Toru Yamashita (山下 亨 , Yamashita Tōru ) (born December 7, 1988 in Osaka), better known by his stage name Toru, is a guitarist and leader in the Japanese rock band ONE OK ROCK. He was in the hip-hop group HEADS along with Ryota Kohama from ONE OK ROCK before they disbanded in 2002.
Document 9: The Associates (band): The Associates were a Scottish rock act, formed in Dundee in 1979 by singer Billy Mackenzie and guitarist Alan Rankine. The group first gained recognition after releasing an unauthorized cover of David Bowie's "Boys Keep Swinging" in 1979, which landed them a contract with Fiction Records. They followed with their debut album "The Affectionate Punch" in 1980 and the singles collection "Fourth Drawer Down" in 1981, both to critical praise.
Document 10: Scottish music (1980–1989): During the 1980s, Scottish music featured post-punk bands exemplified by Simple Minds and Josef K, and bands like Runrig that remained closer to the Scottish dance music tradition. Folk rock or Celtic rock bands launched in the 1980s included The Waterboys and The Proclaimers. Among the folk singers of the time were Dick Gaughan and Bill Drummond, and Ewan MacColl who died in 1989.
Document 11: Billy Mackenzie: William MacArthur "Billy" MacKenzie (27 March 1957 – 22 January 1997) was a Scottish singer, with a distinctive high tenor voice; he was best known as a member of The Associates.
Document 12: Ryuichi Sakamoto: Ryuichi Sakamoto (坂本 龍一 , Sakamoto Ryūichi , born January 17, 1952) (] ) is a Japanese musician, composer, record producer, pianist, activist, writer, actor and dancer, based in Tokyo and New York. He began his career while a university student as a session musician, producer, and arranger in the 1970s, first gaining major success in 1978 as one third of the electronic music group Yellow Magic Orchestra (YMO). The band had worldwide hits such as "Computer Game / Firecracker" (1978), "Behind the Mask" (1978), and "Rydeen" (1979), playing a pioneering role in the development of the synthpop, techno and house genres.
Document 13: Kyosuke Himuro: Kyosuke Himuro (氷室 京介 , Himuro Kyōsuke , born October 7, 1960 in Takasaki, Gunma, Japan) is a Japanese singer-songwriter and musician. He was a lead vocalist of the rock band Boøwy from 1981 to 1988. After the group disbanded he started a successful solo career, becoming one of Japan's best-selling artists. In 2003, HMV Japan ranked Himuro at number 76 on their list of the 100 most important Japanese pop acts. He currently lives in Los Angeles, California, where he purchased a palatial residence in Beverly Hills in 2004, which was previously owned by Shaquille O'Neal.
Document 14: Jimmy Somerville: James William Somerville (born 22 June 1961) is a Scottish pop singer and songwriter. He sang in the 1980s with the pop groups Bronski Beat and The Communards, and has also had a solo career. He is known in particular for his falsetto singing voice.
Document 15: Inoran: Kiyonobu Inoue (井上 清信 , Inoue Kiyonobu , born on September 29, 1970 in Hadano, Kanagawa) , known exclusively by his stage name Inoran, is a Japanese musician, singer and songwriter. He is best known as the rhythm guitarist and a co-founder of the rock band Luna Sea. He started his solo career in 1997 and when Luna Sea disbanded in 2000, he formed Fake? with Oblivion Dust vocalist Ken Lloyd a year later. Then in 2005 when leaving Fake? he founded Tourbillon with Luna Sea vocalist Ryuichi Kawamura and Hiroaki Hayama. He has recently rejoined Luna Sea as they reunited in 2010, and in 2012 formed Muddy Apes with bassist Taka Hirose and support guitarist Dean Tidey, both from Feeder, and 8otto's vocalist Maeson.
ground_truth: Ryuichi Kawamura