Itaru Oki (沖至, Oki Itaru in Japanese order) spent the first half of his career in Tokyo's new-jazz scene and the second half in Paris, and he kept crossing between the two for the rest of his life. He was born on September 10, 1941, in Suma, a ward of Kobe, into a musical household: his father played shakuhachi and his mother taught koto. He took up the trumpet in a high-school brass band, studied architecture in Osaka, and played Dixieland and then bebop around the Kansai region. English Wikipedia names Fumio Nanri, the pioneering Osaka-born trumpeter, as his early teacher, and Oki later put Nanri's name into two of his own titles: "Hohoemu Nanri-san" (Smiling Mr Nanri) on his 1976 quartet album and "Smiling Mr Nanri" again on his 2014 solo record.

By 1965 he was in Tokyo. The Discogs and Wikipedia biographies place him in ESSG, a free-jazz group formed in 1966 with pianist Masahiko Satoh, saxophonist Mototeru Takagi and percussionist Masahiko Togashi, which toured Europe in 1969. His own recording career began in 1970. Trumpet In Modern Jazz (Toshiba), cut with the bassist Keiki Midorikawa and the drummer Hozumi Tanaka, is mostly Oki originals plus "Tenderly" and "Manha De Carnaval". The same trio recorded Satsujin Kyoshitsu ("Homicide Classroom") in Tokyo that February, a far more open set in which Oki is credited with trumpet, flugelhorn, cowbell, triangle, bells and wood block, and Midorikawa doubles on piano and gong. On May 20, 1970 at Yamaha Hall in Ginza, the Oki Trio shared a live workshop bill, released as Trio By Trio + 1, with Yosuke Yamashita's trio, Yuji Ohno's trio and the singer Kimiko Kasai. An Itaru Oki quintet is also credited on the 1973 Inspiration & Power 14 free-jazz festival record, put on by the concert producer Teruto Soejima, who also produced the live date that became Shirasagi.

Shirasagi (Nadja, 1974) was recorded at Akasaka Sogetsu Hall in Tokyo on June 7, 1974, with Shoji Ukaji on baritone saxophone, Takashi Tokuhiro on bass and Tatsuya Nakamura on percussion. Its A side is a single 20-minute title piece. That same year Oki moved to France.

In Paris he taught at the Institut Art Culture Perception, the school run by the bassist and bandleader Alan Silva, and he is credited on Silva's Celestrial Communication Orchestra records of 1979, 1982 and 2003. He also recorded with Noah Howard's quartet, and in June 1976 he was the trumpeter on Paris Days by the expatriate pianist Takashi Kako, a quintet date with Claude Bernard, Kent Carter and Oliver Johnson. English Wikipedia's biography adds tours with Art Farmer, Lee Konitz, Steve Lacy and Sam Rivers, without dates. He did not abandon Japan: two of his Japanese albums of the decade were recorded in Tokyo. Genso Note (Offbeat, 1976), a quartet with the altoist Yoshiaki Fujikawa, Midorikawa and Tanaka, was cut in Tokyo in December 1975, and Mirage (Trio, 1977) followed there on February 8 and 9, 1977, with Kako on piano, Midorikawa on bass and Togashi on percussion. In between, a German date for the FMP label, One Year - Afternoon & Evening, was recorded in Berlin on October 13, 1978 with the bass clarinetist Michel Pilz and the drummer Ralf Hübner.

Not all of the Paris work was free. Opera Night, recorded in Paris on December 6, 1984 and issued in Japan by Paddle Wheel in 1986, is a standards-and-originals quartet with the pianist Alain Jean-Marie, the bassist Jean-Jacques Avenel and the drummer Oliver Johnson. In the early 1990s he joined the pianist Tchangodei and the bassist Kent Carter for Jeux D'Ombres and Perfect Emptiness, the second taken from the Lausanne festival and a 1992 Japan tour. From the mid-1990s he came back to Japan nearly every autumn to tour, and that is where most of the late Japanese records come from: the Concert With Strings date of November 1996 with the guitarist Sadanori Nakamure; a trio concert on January 2, 1996 at Cafe Amores in Hofu with the bassist Nobuyoshi Ino and the trumpeter Choi Sun Bae, issued in 2017 as Kami Fusen; and the Itaru Oki Unit, a sextet with the trumpeter Natsuki Tamura, the pianist Satoko Fujii and the tenor saxophonist Keizo Nobori. Fujii and Tamura play on four of the Unit and Special Group releases from 2004 to 2007. He also made a live duo record with Otomo Yoshihide, Encounter (2007), recorded at Big Apple on November 29, 2005.

Back in Paris, the Improvising Beings label issued much of his work from 2010 on, beginning with Nobusiko (catalog number ib01), a duo with the bassist Benjamin Duboc. Others include the solo Chorui Zukan (2014); Root Of Bohemian, a two-trumpet record with Axel Dörner; Le Chant Du Jubjub, with François Tusques, Claude Parle and the narrator Isabel Juanpera; and D'Une Rive A L'Autre with Kent Carter. He also played on The Sundance 2 (2014), a live trio set with the tenor saxophonist Abdelhaï Bennani and the drummer Sabu Toyozumi, recorded at Babilo in Paris in September 2012. He was known as well for his collection of unusual trumpets, including a double-belled instrument, which was shown in exhibitions in France.

Oki passed away on August 25, 2020, at the age of 78, in Paris. Several records came out after his death. NoBusiness issued a 1975 quartet concert from Fukuoka as Live At Jazz Spot Combo 1975 (2021); Itaru Oki Last Message With Masahiko Satoh, a duo concert from October 2018 at Shibuya Koendori Classics, was released in January 2021; and the Off Note label put out a 2017 trio date, Oogomadara Ça Va. Ça Va ! Cool Cool !, that August. Alan Silva's Celebration (2022), recorded in Paris in May 2019 with Oki, Richard Comte and Makoto Sato, is dedicated to his memory.

Oki came out of bebop and Dixieland and never lost the ability to play a standard straight: Opera Night, Concert With Strings and the 2019 double album Les Yeux de La Nuit are built on "I Remember Clifford", "Misterioso", "Soul Eyes" and "The Night Has A Thousand Eyes". The free records are a different register. On Satsujin Kyoshitsu and Shirasagi the trumpet shares the space with bells, wood blocks, an Indian flute and percussion; on later records he adds shakuhachi, bamboo flute, a length of rubber hose and tubes to the trumpet and flugelhorn. He often played with people from outside jazz as well, among them the poet Kazuko Shiraishi, who reads on Hito-ka no Kuma (2003) and on Live At "Aketa" (2007).

The piece "Ontakesan" recurs across his later work. It appears on Concert With Strings in a sextet arrangement with strings, on the Itaru Oki Unit's Live, and on Live At "Aketa" in a quintet with piano and guitar, so the same theme was re-voiced for each lineup. His later solo and duo records for Improvising Beings are made of short pieces: Chorui Zukan has fourteen tracks, mixing Japanese-titled pieces with standards such as "Misterioso" and "Round Midnight".