Jiro Inagaki was born in Tokyo on October 3, 1933, and registered under the name Inagaki Yukio. He taught himself the saxophone and was working professionally before he finished high school, which put him on the Tokyo bandstand at the exact moment postwar Japanese jazz was inventing itself.

Through the 1950s he worked in the bands of drummer George Kawaguchi, drummer Hideo Shiraki, actor and bandleader Frankie Sakai, pianist Masao Yagi and guitarist Shungo Sawada. He was also an early member of Hana Hajime's Cuban Cats, the group that became the Crazy Cats, Japan's biggest comedy-music act of the 1960s. In 1962 he formed the Jiro Inagaki Quintet with pianist Yo Tokuyama and bassist Yasuo Arakawa, and the following year he played in Lionel Hampton's Japan tour band, a credit preserved on the live album Hamp In Japan (1965). He also recorded with Helen Merrill on Helen Merrill In Tokyo (1963), playing tenor saxophone and flute.

His model as a player moved from Sonny Stitt to Sonny Rollins, and stopped there. When John Coltrane pushed into modal and then free playing, Inagaki lost interest, saying decades later that by the time Giant Steps arrived he had had enough of trying to copy it. By the late 1960s he had spent close to twenty years as a working bebop saxophonist and had come to feel the Japanese scene had stopped moving.

The change came from a 1969 tour of the United States with drummer Takeshi Inomata. Inagaki heard Blood, Sweat & Tears, Tower of Power and Cold Blood building horn sections into rock bands, and he came home and founded Soul Media that same year. He had already tested the idea: This Is Jazz-Rock, credited to Jiro Inagaki & The All-Stars with arranger Norio Maeda, came out in 1968.

On September 14, 1970, Inagaki convened a session at Nippon Columbia's Tokyo studio with the visiting American saxophonist Steve Marcus, who was in Japan touring with Herbie Mann and Woody Herman. The band recorded onto a prototype PCM digital tape machine borrowed from the NHK Technical Research Institute. Released as an ordinary analog LP in January 1971 under the title Something, it was the first commercially issued digital recording made anywhere in the world, eleven years ahead of the Compact Disc. The sleeve carries the note "Master Sonic PCM Recording." Masahiko Satoh played piano and electric piano and wrote the arrangements, and Ryo Kawasaki played guitar.

Between those two dates came the record Inagaki is best known for among collectors. Head Rock was cut at Tokyo Studio Centre on August 6 and 7, 1970, with Inagaki on tenor and soprano, Tetsuo Fushimi on trumpet, Masaru Imada on organ, a 23-year-old Ryo Kawasaki on guitar, Yasuo Arakawa on bass and Sadakazu Tabata on drums. Two weeks earlier, on July 21, a twelve-piece version of the band had played the Midsummer Night's Jazz & Rock concert at Hibiya Amphitheater with Shunzo Ohno added on trumpet, and Nippon Columbia released the tape as Jazz & Rock "Out".

The Soul Media run that followed moved quickly and did not repeat itself. Wandering Birds (December 1971) added vocals from Sammy and Yasushi Sawada. Dōsojin (June 1972) reworked Japanese folk material. By The Red Stream (April 1973) was written, arranged and conducted by Hiromasa Suzuki for a fifteen-piece band. In The Groove (1973) traded psychedelic jazz-rock for Crusaders-style soul jazz. Funky Stuff, recorded in August 1974 and released in January 1975, is the summary statement: Hiromasa Suzuki arranging and playing Fender Rhodes, Inagaki producing and writing his own sleeve notes, and a title track borrowed from Kool & The Gang. Its third cut, "Breeze," has passed 16 million streams on Spotify.

Running underneath all of it was a second career on the same label. Discogs lists 31 releases under Inagaki's own name, and the large majority are easy-listening tenor-sax and kayōkyoku albums for Nippon Columbia: Golden Tenor Saxophone, Sentimental Tenor Mood, Tenorsax Fancy Mood, and volume after volume of hit-parade covers. He worked constantly as a session player and producer in Japanese pop, appearing on Eiichi Otaki's Niagara Moon (1975), Minako Yoshida's Minako (1975) and Flapper (1976), Kenji Sawada's records, and Niagara Triangle Vols. 1 and 2, and producing Pink Lady In Disco (1978) as well as five albums for the singer Kei Marimura. His horn section, billed as 稲垣次郎セクション, became a fixture of Otaki's Niagara productions and of Tatsuro Yamashita's early records. In 1972, at the height of the jazz-rock run, he announced that he would stop playing rock concerts.

The later leader dates are quieter and stylistically apart. Blockbuster (1978) was recorded at Toshiba EMI Studio on July 25 and 26 with Chuck Rainey's rhythm section and Norio Maeda's arrangements. Memory Lane (1980) closed out Soul Media. Jazzy (1981), billed to Jiro Inagaki & Just Friends, is a straight standards session with Yuji Ohno at the piano.

For roughly three decades the jazz-funk catalogue was almost unknown outside Japan. The route back was Yusuke Ogawa, who runs the Tokyo record shop Universounds and began reissuing this material through his Deep Jazz Reality series in the 2000s. International labels followed. In 2023 the French imprint 180g released WaJazz Legends: Jiro Inagaki, a gold double LP that Ogawa selected and annotated track by track, with Inagaki's own comments printed alongside. It came out on October 3, 2023, Inagaki's ninetieth birthday.

He passed away 107 days later, on January 18, 2024, of pneumonia. He was the last confirmed surviving member of the original Cuban Cats lineup.

Inagaki's playing came out of American hard bop tenor. Sonny Stitt was his first model, Sonny Rollins his second, and he was open about where he stopped following the music: Coltrane's move into modal and free playing did not interest him, and he said so plainly rather than pretending otherwise. That refusal shaped what came next. Instead of chasing harmonic complexity he went after rhythm and mass, which is why Soul Media sounds less like a jazz group playing rock tunes and more like a horn section behaving as a rhythm section.

The Soul Media sound is built from fuzz guitar, Hammond and Fender Rhodes, hard drum breaks, and a tightly voiced brass line that punches rather than floats. Its American reference points are explicit: Blood, Sweat & Tears and Tower of Power for the horns-in-rock idea, Kool & The Gang and the Crusaders for the funk and soul-jazz turn after 1973. What keeps the records from being derivative is the writing and arranging he brought in from the Japanese scene, particularly Hiromasa Suzuki, whose charts for By The Red Stream and Funky Stuff give the band its distinctive weight, and Masahiko Satoh, whose electric-piano playing on Something pushes the group toward free territory the studio dates rarely reach.

His tone across all of it stayed warm, broad and vocal, which is exactly what made him employable on hundreds of easy-listening and pop sessions in the same years. The two halves of his career were never really at war; the same big tenor sound carried both.