Kazuo Imai (今井和雄) is a Tokyo-based guitarist who has spent half a century in free improvisation, working in the space between two traditions that rarely share a stage: the free jazz of his teacher Masayuki Takayanagi and the experimental, conceptual music of Takehisa Kosugi. He was born on September 24, 1955, in Kawasaki, Kanagawa Prefecture.

His first instrument was a gut-string guitar that an uncle gave him in 1968, in his first year of junior high school, and at first he played rock on the electric guitar. Two years later a friend who loved jazz took him to a jazz cafe, and he began going almost every day. His favorites were the 1960s records of John Coltrane and the late-1960s John McLaughlin, heard with the Miles Davis group and with Lifetime. In September 1972 he enrolled at the Yamaha Jazz School, where, by his own later account, Sadao Watanabe was the main teacher. His guitar instructor there was Takayanagi, and two years later, on Takayanagi's recommendation, he left Yamaha for Takayanagi's own private school and soon became his assistant. That gave him a seat for the performances of Takayanagi's collective improvisation group New Direction, which he has described as an enormous influence.

The lessons themselves were strict. They began with classical practice books, learning to play with a pick instead of the fingers, and only scales and arpeggios; once he finished the books he chose a conventional or experimental classical score to play with the pick, then another, and in the last years he worked only on J.S. Bach. In June 1985, thirteen years after his first lesson, he graduated, the only graduate in the school's history.

A second teacher pulled the other way. Imai met Kosugi in 1975 at the Mato Grosso Gallery in Tokyo, where Kosugi had an exhibition, and from April of that year he attended Kosugi's workshop at the Bigakko art school in Kanda. In March 1976, partly as a graduation presentation, he and other students gave collective free-improvisation concerts under the name East Bionic Symphonia, and they recorded in July 1976 at Bigakko, the session that became his first recording. He did not play the guitar at any of it. He used a replica viola da gamba that he happened to come across, small ethnic instruments and his own voice, because he wanted to make music that did not depend on playing skill. A month after he joined the workshop, Kosugi suggested that Imai take his place in a Taj Mahal Travellers concert, and until late 1977 he made monthly guest appearances with the band, again on instruments other than guitar. For six months in 1976 he also guested with Takayanagi's New Direction as a vocalist, declining Takayanagi's advice to play guitar for fear of sounding too much like him. In his own words he was a guest with both groups, never an official member.

The next years were quiet by choice. He worried that he was following the lead of two highly influential musicians instead of finding his own voice, and from 1978 he played in public less and less. There was six months with the drummer YAS-KAZ's Dagakutobo studio in 1977, guest guitar with the band AXTH of the late Akira Iijima in 1981 and 1982, and in April 1983 the group Leaf Well Island with Iijima and the bassist Kazuki Chiba, in which he again played viola da gamba rather than guitar. After his graduation from Takayanagi's school in 1985 he withdrew from the live scene entirely. He came back in December 1991 with a series of solo concerts called Solo Works, which was still running when the 33rd concert was held in March 1999 and reached its 41st on April 24, 2004, at Plan B in Tokyo.

The 1990s brought a recording career. His first solo album, How Will We Change? (Solo Improvised Works), came out on P.S.F. Records in 1995 and was taken from Solo Works concerts of September 25 and October 23, 1993. From 1996 to 1998 he played in the bandoneon, guitar and bass trio Tango Moderno, and he played with visitors to Japan: the alto saxophonist Lee Konitz in 1996, the tenor saxophonist Arthur Doyle in 1997, the pianist Irene Schweizer in 1998 and the bassist Barre Phillips in 1999. The Konitz meeting was recorded at ST Spot in Yokohama on October 24, 1996 and released by P.S.F. as Unaccompanied Live in Yokohama (1997), with Imai credited on guitar. The Phillips duo, all of it improvised, was recorded at Yellowknife Studio in Tokyo on May 20, 1999 and released as Play 'Em As They Fall. He is also the guitarist on one track of Otomo Yoshihide's 1999 tribute to the television composer Takeo Yamashita.

In October 1997 he organized a four-hour concert called Marginal Consort, reuniting the participants of the 1976 East Bionic Symphonia performance for an evening of nothing but collective free improvisation, and held a second in September 1998. The group, drawn from his Bigakko colleagues including Masami Tada, Kei Shii and Yasushi Ozawa, kept going and now meets once a year for performances of two to four hours with only the start and end times fixed. Its recorded history runs from Collective Improvisation (P.S.F., 1998, recorded October 18, 1997 at Asahi Square in Asakusa) through a four-disc set of 2003 and 2004 performances (Improvised Music From Japan, 2007), a concert at the INSTAL festival in Glasgow on February 17, 2008, and a set at the South London Gallery on September 8, 2013. On June 1, 2018, the group made its American debut at Pioneer Works, followed by a second show in Los Angeles on June 3.

From the 2000s on, his discography is a series of duos and small groups with improvisers from Japan and abroad. With the Dutch drummer Han Bennink he recorded Across the Desert at Earth Studio in Tokyo on May 27, 2002 (Improvised Music From Japan, 2003). With the pianist Shuichi Chino he played a concert at the Tokyo University of the Arts on November 11, 2000, issued as 001111 (P.S.F., 2004). On May 19, 2003, at the Festival International de Musique Actuelle de Victoriaville in Quebec, he played in a quintet with the koto player Kazue Sawai, the saxophonist Michel Doneda, the percussionist Lê Quan Ninh and the bassist Tetsu Saitoh, released as Une Chance Pour L'Ombre (Les Disques Victo, 2004). The partnership with Saitoh became a series, the Orbit records on Saitoh's Travessia label: Orbit 1 (with Doneda, 2006), Orbit 2: Voyaging Antipodes (2006) and Orbit Zero (2011), recorded at Plan B in Nakano on December 28, 2009. In 2004, at the request of P.S.F. founder Hideo Ikeezumi, he released Far and Wee, a solo set on nylon-string classical guitar recorded at the Solo Works concert of April 24, 2004; the Black Editions label reissued it on vinyl on July 31, 2020.

Alongside the acoustic work he leads the Imai Kazuo Trio with Atsuhiro Ito on optron (a homemade instrument built from fluorescent tubes) and Manabu Suzuki on electronics, which recorded the double-disc Blood (Doubtmusic, 2008) in July and August 2008 at GOK Sound in Tokyo. The program includes "Subconscious Lee," "Well You Needn't" and "So In Love," next to material credited to Annette Peacock. With the bassist Nobuyoshi Ino, the trumpeter Axel Dörner and the drummer Noritaka Tanaka he recorded Rostbeständige Zeit at Plan B on April 16 and 17, 2008, released by Doubtmusic in 2010.

The recent decade has two sides. The solo records of the Hitorri imprint are For Tentou Mishima (2016), music he made for a private exhibition at Nanzuka Agenda in Tokyo on August 7, 2010, in which he plays acoustic guitar, fiedel gamba, branches and piano wire, and The Seasons Ill (2017), two long pieces for electric guitar. With the British drummer Roger Turner he recorded Molecules live at Bar Isshee in Tokyo on October 11, 2017 (Ftarri, 2018), and on June 12, 2019 he played a solo guitar concert at the People's Republic of Australasia in Sydney. His quartet, with Ino on contrabass, a reed player credited as 藤堂勉 and the drummer Yamazaki, recorded live on December 3, 2020 and issued Has the Future Become the Past on Jinya Disc in November 2022, the label that also issues Takayanagi's archive recordings. Imai wrote the liner notes for several of those Takayanagi releases: A Jazzy Profile of Jojo (2005), Angry Waves Vol. 1 and Vol. 2 (2016), and Not Blues (2018). The most recent records are Be Quiet!!! (Meenna, 2023), a trio with the tenor saxophonist Junji Hirose and the drummer Darren Moore recorded on August 4, 2022, and Go Home and Go to Bed !!! (Ftarri, 2024), a duo with Hirose recorded live at Ftarri in Tokyo on December 11, 2021.

Imai's own biography describes music that combines excellent technique with the passion of free jazz and the textures of ethnic and avant-garde classical music, delivered with a high degree of abstraction, density and tension. His technique covers fingering and picking, hitting and scratching the strings with a pick or with one or both hands, bowing, placing sticks under the strings and using effects pedals, and the sleeve of Far and Wee describes sounds drawn from the pegs, the bridge and the strap pin. The liner notes to Molecules credit him with creating "a whole tonal universe on just a single nylon-strung acoustic guitar." Besides guitar he plays the replica viola da gamba and live electronics.

His formation explains the double identity. From Takayanagi came the discipline of the pick and the Bach scores, the jazz-school background and the free-jazz attitude; from Kosugi came the open, collective, instrument-agnostic improvisation of East Bionic Symphonia and Marginal Consort. Early on he listened to Coltrane and to the McLaughlin of the Miles Davis band, and the program of the trio's Blood sets "Well You Needn't" and "So In Love" beside experimental material. His work sits squarely in the free-jazz and improvised-music catalogs: his leader and duo records are filed under jazz and free improvisation, released on labels such as P.S.F. Records, Improvised Music From Japan, Les Disques Victo and Ftarri, and made with improvisers from the jazz and free-improvisation world including Lee Konitz, Barre Phillips and Han Bennink. He has also appeared as a guest guitarist on a few records far from that world, such as a noise-group box set and an anime soundtrack, which are peripheral to the main body of his work.