Question: Are Toshiko Koshijima and Guy Chadwick both responsible for writing the majority of their respective bands material?

Context articles: Toshiko Akiyoshi – Lew Tabackin Big Band
World of Fantasy (album)
Toshiko Ueda
Cutie Cinema Replay
Yasutaka Nakata
Toshiko Sato
Guy Chadwick
Stereo Worxxx
Capsule (band)
Toshiko Koshijima

The Toshiko Akiyoshi – Lew Tabackin Big Band was a 16 piece jazz big band created by pianist Toshiko Akiyoshi and tenor saxophone/flutist Lew Tabackin in Los Angeles in 1973.
 In 1982 the principals moved from Los Angeles to New York City and re-formed the group with new members under the name, The Toshiko Akiyoshi Jazz Orchestra featuring Lew Tabackin.
 Akiyoshi arranged all of the music for the band and composed nearly all of the music recorded by the two groups over a 30-year period.
 Tabackin served as the bands' featured soloist on tenor saxophone and flute.
 The groups recorded 23 albums, toured in North America, Japan and Europe and, after the move to New York, had regular performances at the jazz club Birdland before disbanding in 2003.
 The bands' recordings received several Grammy nominations and regularly scored high in "Down Beat" magazine's critics' and readers' polls.
World of Fantasy is the twelfth studio album by the Japanese electronica band Capsule, released on May 25, 2011, in Japan.
 The album was originally due for release with the title of "Killer Wave".
 After the 2011 Tōhoku earthquake occurred on March 11, 2011, Yasutaka Nakata announced that the album's release (which was previously announced as March 23, 2011) was postponed and due for release at an unknown date for cover art rework and renaming.
 "Killer Wave" was then considered a "working title".
 This is the only album of the duo with all songs sung by the vocalist Toshiko Koshijima.
 It is also their first completely English-language album.
Toshiko Ueda (上田 トシコ , Ueda Toshiko , August 14, 1917 – March 7, 2008) was a Japanese manga artist who helped shape the face of modern shojo manga.
 She wrote under three pen names: 上田としこ for manga, 上田とし子 when writing for newspapers, and later 上田トシコ , all three of which are read as Toshiko Ueda in English.
Cutie Cinema Replay is the second album by the Japanese electronica band Capsule.
 The album was released in 2003 and, unlike the other releases of the group, nearly every track features a guest vocalist.
 Toshiko Koshijima sings on only two tracks, "Plastic Girl" and "Music Controller".
 Some tracks on the album have a French theme, with the intro and outro both spoken in French by the group member and producer Yasutaka Nakata, while "French Lesson" has "123" and "ABC" being said in French with accordion being played in the background.
Yasutaka Nakata (中田 ヤスタカ , Nakata Yasutaka , born February 6, 1980 in Kanazawa, Ishikawa) is a Japanese DJ, record producer, composer and songwriter.
 He formed the band Capsule in 1997 with vocalist Toshiko Koshijima and himself as composer and record producer when both were 17.
 They formally debuted in 2001 with the song "Sakura."
Toshiko "Tosh" Sato (佐藤 とし子 , Satō Toshiko ) is a fictional character from the television series "Doctor Who" and its spin-off "Torchwood", played by Naoko Mori.
 After a one-off appearance in the "Doctor Who" episode "Aliens of London" (2005), Toshiko is re-introduced as a series regular in the "Torchwood" 2006 premiere episode "Everything Changes".
 The character appears in every episode of the show's first two series as well as Expanded Universe material including "Torchwood" novels, audiobooks and comic strips.
Guy Stephen Chadwick (born 21 March 1956 in Hanover, Germany) is an English singer, songwriter and guitarist, best known as the frontman of alternative band, The House of Love, for which he wrote the majority of the band's material.
Stereo Worxxx (sometimes titled as Stereo Works) is the thirteenth studio album by electronica band Capsule.
 It was released on March 7, 2012, by Yamaha.
 Produced, composed and written by Capsule member Yasutaka Nakata, "Stereo Worxxx" was the duo's last album with their label Yamaha until transferring with Warner Music Japan and Nakata's own label, Unborde.
 Musically, "Stereo Worxxx" focuses on electronic dance music and house music with Capsule member Toshiko Koshijima singing on all tracks apart from "Motor Force".
Capsule (カプセル , Kapuseru ) is a Japanese electronica band consisting of record producer Yasutaka Nakata and vocalist Toshiko Koshijima.
Toshiko Koshijima (こしじま としこ , Koshijima Toshiko , born March 3, 1980 in Kanazawa, Ishikawa) is a Japanese singer.
 Along with composer, record producer and DJ Yasutaka Nakata, she is a lead vocalist of the electronica band Capsule, which they formed in 1997 when both were 17.
 Their formal debut came in 2001 with the release of the single "Sakura".
 Two more singles and their debut album, "High Collar Girl", followed the same year.