Ayako Hosokawa (細川綾子) learned jazz in front of American servicemen. She was born in Azabu, in Tokyo, in 1938, and at 14 she took lessons from the songwriter Kunosuke Hamaguchi and began singing professionally at U.S. military camps in Japan. By her mid-teens she was a vocalist with Shigenori Ohara and the Blue Coats, a popular big band led by Masao Kojima, and in 1956 she recorded for Columbia in Tokyo with Jin Watanabe and the Six Joes. She loved jazz and wanted to sing it where it came from. In about 1960, at 22, she married an American, which made the move possible, and she settled in San Francisco.

The United States gave her what Tokyo could not. She sang jazz for a living on the West Coast, and by 1965 she was working with the pianist Earl Hines, appearing with him in Las Vegas and serving as his featured vocalist until about 1967. It was an unusual place for a Japanese singer to land. She spoke later of discrimination she met as a Japanese woman in those years, and of being on stage singing when she heard that President Kennedy had been assassinated. Through the 1960s and 1970s she was better known on the American West Coast than at home.

That changed in 1977, when she came home for a visit and made a record. Takeshi Fujii, the producer behind the audiophile label Three Blind Mice, gave her a debut as a leader at 39. To Mr. Wonderful (TBM-3008) was recorded on June 9 and 10, 1977, at Epicurus Studios in Tokyo, with arrangements by the guitarist Shoji Yokouchi, Tsuyoshi Yamamoto on piano, Konosuke Saijo on tenor saxophone, Isoo Fukui on bass, Tetsujiro Obara on drums, and a small string section. Its nine tracks mix standards ("Misty," "My Foolish Heart," "The Lady Is a Tramp") with pop songs of the day, among them Simon and Garfunkel's "Bridge Over Troubled Water" and Roberta Flack's "Feel Like Makin' Love," all in English. Japanese listeners noticed her English pronunciation and her swing, and the record has been reissued on LP and CD several times since.

Two more Three Blind Mice albums followed in quick succession. No Tears was recorded on December 27 and 28, 1977, at Toshiba EMI Studio in Tokyo with the Masaru Imada quartet and issued in 1978. Imada played piano, Obara drums, Mitsuaki Furuno bass and Yuji Imamura percussion. Call Me, recorded on January 6 and 7, 1979, at Epicurus Studios, put her in front of a big band: Toshiyuki Miyama conducting The New Herd, with Natsuki Tamura in the trumpet section and arrangements by Kozaburo Yamaki, with Tommy Smith credited on three tracks. A medley on that album, "Feel Like Makin' Love / I Wanted It Too / No Tears," folds the two earlier records into one.

She returned to Tokyo for good in the mid-1980s and spent roughly a decade based there, working clubs such as the Roppongi room All of Me and appearing at festivals. A German-language reference entry credits her with a 1987 Monterey Jazz Festival appearance, about twenty-five years as an attraction at the Kobe Jazz Street festival, regular dates at the Nara Jazz Festival and the Breda Jazz Festival in the Netherlands, and a Tsumara Jazz Vocal Award in 1991.

In July 1993 she travelled to San Francisco to record A Whisper of Love at Different Fur Recording Studio on July 1 and 2, her last album for Three Blind Mice. It paired her with pianist Donald T. Carson, bassist John Hettel, drummer Jimmie Smith and reed player Ray Loeckle, with the pianist and arranger Shota Osabe on several tracks, and it reached beyond the standards book to "Sea of Love" and Eric Clapton's "Tears in Heaven." In the late 1990s she moved back to the United States, living in the San Jose area and returning to Japan about twice a year to sing. The audiophile label First Impression Music drew on her Three Blind Mice recordings for A World of Love (1997), and issued I Touch the Stars (2005), a new album recorded with the Shota Osabe Piano Trio. Little Things Mean a Lot, a hybrid SACD on the T.S.C.C. label, appeared in 2001.

In her late seventies she was still making the trip home. In November 2016 she took part in a Jamboree at Asakusa Public Hall in Tokyo, and a few days later sang at the homecoming concert of her San Francisco collaborator Shota Osabe. Ayako Hosokawa passed away on November 28, 2020, Japan time. Disk Union, the Japanese record chain, published a memorial notice on December 2. Her Three Blind Mice albums had by then been reissued repeatedly, and To Mr. Wonderful was pressed again on LP and SACD in 2024.

Hosokawa sang in the middle of the vocal jazz tradition: ballads and medium swingers from the American songbook, delivered in a clear, warm, unforced voice with unusually natural English diction for a singer from Tokyo. Her records are built around the standards she learned in the American camp clubs and on the West Coast, and her Three Blind Mice records were engineered for close, natural sound, which made them favourites with audiophiles as well as jazz listeners.

She was equally willing to take on pop songs from her own era and treat them as jazz material. "Bridge Over Troubled Water," "Feel Like Makin' Love," "Just the Way You Are," "Sea of Love" and "Tears in Heaven" all sit comfortably between "Misty" and "Georgia on My Mind" on her records. The three Three Blind Mice albums show three settings for the same voice: a string-and-rhythm studio date, a piano quartet, and a full big band. Her years with Earl Hines tie her to an older generation of jazz, while the repertoire on her records belongs to the 1970s.