Question: Who has been involved in more music groups, Ryuichi Kawamura or Billy Mackenzie?
Context: Aionism is the third album released by the metal band Aion.  The first pressing released on October 8, 1991, included a sticker and cardboard slipcover.  A remastered version was released on June 6, 1995.  It is arguably the band's most successful album, reaching number 37 on the Oricon chart.  A promotional video for "Be Afraid" was made to promote the album.  Ryuichi Kawamura, vocalist of the rock band Luna Sea, provides background vocals for the song "Disarray".  Likewise every Luna Sea member does the same for the tracks "Launch Game", "S.S.S" and "Caution". 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). "Break the Chain" is a song by Japanese rock band Tourbillon, and was the band's fifth and final single.  It was released a year-and-a-half following the release of their second album "A Tide of New Era", and was used as the opening theme for the 2008 television series "Kamen Rider Kiva".  Ryuichi Kawamura stated that the song was not just the "let's beat up the bad guys!"  kind of Kamen Rider Series opening theme, but a song that both children and adults can enjoy. Carsten Nicolai (September 18, 1965), known as Alva Noto, is a German musician.  He is a member of the music groups Diamond Version with Olaf Bender (Byetone), Signal with Frank Bretschneider and Olaf Bender, Cyclo with Ryoji Ikeda, and Alva Noto + Ryuichi Sakamoto with Ryuichi Sakamoto, with whom he composed the score for the 2015 film "The Revenant". 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. Chain was Edinburgh musician Paul Haig's third album and was released in May 1989 on Circa Records, a subsidiary of Virgin Records.  "Chain", which Haig financed himself, was recorded and completed in 1988, but it sat on the shelf after the normally accommodating Les Disques Du Crepuscule decided not to take up the option of releasing it.  The album was co-produced by long-time Haig cohort, Alan Rankine, instrumentalist with celebrated Dundee band, The Associates.  There was another Associates connection on the album - the track "Chained" was written by Haig's good friend, Billy Mackenzie.  Haig returned the favour and gave Mackenzie the track "Reach The Top" for his album "The Glamour Chase", which after many years in limbo was finally released in 2002. Trip Trip (stylised as trip trip) is Kokia's second album, released in January 2002.  It was her first album released with Victor Entertainment, and her only released under Gai Records management (though Kokia worked with both companies for her collaborations with Ryuichi Kawamura on his ЯKS album, "Kanata Made", in 2000).  Unlike "Songbird", the album was self-produced. 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. 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. One Second is Yello's fifth original studio album, having been preceded by a 'new mix' compilation the previous year.  Released in 1987, the album is noteworthy for featuring both Billy MacKenzie and Shirley Bassey, the latter singing vocals on "The Rhythm Divine".
Answer: Ryuichi Kawamura