Hiroaki Mizutani (水谷浩章, Mizutani Hiroaki in Japanese order) is a double bassist and electric bassist, composer, arranger and producer, born in 1963 in Saitama Prefecture. He began playing music around the age of 20 and studied double bass with Hiroshi Yoshino (吉野弘志). His working life has two faces that rarely meet in one musician. For more than twenty-five years he has been the bass chair in Otomo Yoshihide's New Jazz Quintet, a free-jazz group that tours Europe and China year after year. He is also the leader of phonolite, a jazz orchestra of ten to twelve players with woodwinds, brass and strings, and of a small string ensemble, phonolite strings, and he runs his own label, mizmzic.

He formed his first group, LowBlow, in 1986: Mizutani on bass, Akira Sotoyama on drums, and the saxophonists Kenichi Matsumoto and Masakuni Takeno, later joined by the guitarist Ryoichi Saito and Taisei Aoki on trombone and keyboards. Its album Cafe Ojisan (Mister Cafe) came out on Off Note in December 1997. Between 1987 and 1993 he worked in the bands of the guitarists Koichi Hiroki and Isao Miyoshi, the pianists Daisuke Iwasaki and Fumio Karashima, the saxophonist Takao Uematsu and the flutist Tamami Koyake, and he plays on the compilation Now's the Time Workshop (Fun House, 1990) and on Koyake's Lady's Blues (Paddle Wheel, 1993). In 1994 he recorded A Day in Aketa with the saxophonist Koichi Matsukaze's trio for the Aketa's Disk label, taped at the Tokyo club Aketa no Mise between November 1993 and June 1994, and began an association with Matsukaze that runs on through the quartet records Private Notes (2005) and Guesthouse De Hirune (2006). In 1994 he also played with the pianist Kei Akagi and took part in John Zorn's game pieces Cobra and Bezique, and in November 1997 he organised a Tokyo staging of Cobra.

In 1995 he joined Tipographica, the band led by the guitarist Tsuneo Imahori, with Akira Minakami on keyboards, Naruyoshi Kikuchi on saxophone, Osamu Matsumoto on trombone and Sotoyama on drums. He is on The Man Who Does Not Nod (Pony Canyon, 1995) and God Says I Can't Dance (1996), and the band toured France in 1997. Around the same time he played on Carmen Maki's Unison (1996) and Elliott Sharp's Spring & Neap (zOaR, 1997). From 1997 he took part in a project by the pianist Takashi Kako with Ushio Amagatsu of the Sankai Juku dance company, and in 1998 he joined the pianist Hiroshi Minami's quartet, recording Go There! (EWE, 2001) and Celestial Inside (2002) and travelling to the Beijing International Jazz Festival in November 1998 and to Denmark in January 2002.

1999 was the year the two long associations began. He joined the pianist Yosuke Yamashita's Duo Plus, then the 4G Unit from 2000, and played festivals at home and abroad with those groups. In the same year he joined Otomo's New Jazz Quintet and toured Europe with it, including the Music Unlimited festival in Wels, Austria, in November. The quintet's first record with him, Flutter (Tzadik, 2001, recorded in February 2000), has Otomo on guitar and electronics, Kenta Tsugami on alto saxophone, Naruyoshi Kikuchi on tenor saxophone and Yasuhiro Yoshigaki on drums, with John Zorn as executive producer. ONJQ Live (DIW, recorded at Shinjuku Pit Inn on 17 March 2002) and Tails Out (DIW, 2003) followed, then ONJQ Live in Lisbon (Clean Feed, 2006), taped at the Jazz em Agosto festival on 6 August 2004 with the Swedish saxophonist Mats Gustafsson sitting in. He also plays in Otomo's larger formations, the New Jazz Ensemble (Dreams, Tzadik, 2002) and the New Jazz Orchestra, for whose two 2005 albums, ONJO and a reading of Eric Dolphy's Out to Lunch (both Doubtmusic), he wrote horn arrangements.

The quintet's present line-up has the trumpeter Shinpei Ruike and the trombonist Osamu Imagome in the front line, with Mizutani on double bass and Yoshigaki on drums. Hat and Beard (F.M.N. Sound Factory, 2020) was recorded in Tokyo on 26 November 2018, the five-LP box Live in Poland appeared in 2024, and El Derecho de Vivir en Paz (2025) was cut in Kyoto on 15 December 2024. In 2025 the group toured Europe twice and China once, including the Bimhuis in Amsterdam on 22 May, and it is due at Jazzfest Berlin on 30 October 2026 as the first stop of a European tour that runs to 7 November. The Berlin festival house is not new to him: part of the New Jazz Orchestra's Live Vol. 2: Parallel Circuit (Doubtmusic, 2007) was recorded there on 17 March 2006.

phonolite was founded in March 2003 as a vehicle for his own writing. The first album, While I'm Sleeping (Studio Wee, 2003), was recorded at GOK Studio in Tokyo on 4, 24 and 25 March with the guitarist Sadanori Nakamure, Sotoyama, Takeno on soprano saxophone, the flutist Miyako Morita, Matsumoto on trombone, a cellist and a percussionist; Mizutani arranged it and co-produced it, and the booklet carries texts by Yamashita, Otomo, Kikuchi, Kahimi Karie and Takeshi Shibuya. My Heart Belongs to Daddy (Studio Wee, 2006), billed to phonolite trio and ensemble, was recorded at Shinjuku Pit Inn on 27 June 2006 and at Ton Meister on 25 July, with Matsukaze on alto saxophone and clarinet. Still Crazy followed on EWE in the autumn of 2008, with a release tour through Tokyo, Kanazawa, Kyoto and Nagoya, and the ensemble recorded again with Tsugami's group Bozo for BOZO & Phonolite Ensemble (EWE, 2009). In 2010 he added phonolite strings, an unusual string quartet of viola, two cellos and double bass, and started mizmzic, whose first release was Uzuraginu (2011), a duo album with the vocalist Yuki Saga. The album phonolite strings followed in 2012, and the strings group has backed Ichiko Aoba (at the Fuji Rock Festival in 2021, at Blue Note Tokyo in 2022 and on the 2025 album Luminescent Creatures), Mariko Hamada, Ikuko Harada and Yoichiro Yanagihara.

Around these two poles he has been a first-call bassist for a wide list of leaders. He joined the saxophonist Akira Sakata's trio in 2009 and recorded Chotto! (I'm Here!) with him and the pianist Kyoko Kuroda (Daphnia, 2010). He plays on the Masahiko Togashi Trio's Live at Köln (JamRice, 2004), with Yamashita at the piano, and he has also played in Takeo Moriyama's group and, from 2016, in Yamashita's quartet. On the Shenzhen cassette Burning Bookshop (Old Heaven Books), recorded on 15 October 2017 after the Yamashita quartet's set at the OCT-LOFT jazz festival, he improvised with Ruike, the drummer Shinnosuke Takahashi and two Chinese players. He has been in the bands of Yoshigaki (Vincent Atmicus and Emergency!), Naruyoshi Kikuchi, Eiichi Hayashi and Tsugami's Bozo, and on the pianist Takashi Matsunaga's trio records Love Makes the Earth Float (2008) and Good News! (2013). Since 2022 he has led a trio with the pianist Saki Ozawa, with Hayato Yamazaki on drums for the 2024 tour. Gush!, a trio with the guitarist Takayuki Kato and Yoshigaki, recorded Boléro live at Shinjuku Pit Inn on 29 January 2018 for mizmzic. He has played a multi-night engagement at Shinjuku Pit Inn under his own name in most years since 2007.

He has taught as well as played. In April 2002 he became a part-time lecturer on the jazz course at Senzoku Gakuen, and since September 2002 he has taught double bass and electric bass at Hot Music School in Tokyo. In April 2019 he moved to Ina in Nagano Prefecture and has since split his time between Ina and Tokyo. In Ina he has played the Inamachi Bara Jazz Street festival, led a fourteen-player unit in a performance of Zorn's Cobra at a 2024 screening of Zorn's documentary trilogy, and directed the music for the town's Creation Forest in 2025; in 2026 he began coaching junior and senior high school big bands and brass bands in the area. His recent releases are Crystal Chant (2024), with Sakata and the pianist Taeko Kurita as the trio Suisho no Yomi (水晶の詠), and Kyo no Koe, Ashita no Koe (December 2025), with a boy soprano and an alto singer as the trio Ao to Mako (あをとまこ). His published schedule for autumn 2026 runs from the Berlin date through nights in Tokyo and Nagano and includes a Suisho no Yomi concert with Sakata at the Jimbocho gallery Gekkasha on 22 November.

Mizutani plays both the double bass and the electric bass, and the range of his credits follows from it. His record dates run from the free improvisation of Tails Out and Live in Lisbon, through the contemporary post-bop of Minami's quartet and Matsukaze's trio, to the written orchestral jazz of phonolite and the chamber writing of phonolite strings. Japanese Wikipedia and the Hot Music School profile describe a sound known for groove and breadth, and he names Yoshino as his teacher.

His writing is a different matter from his playing. In phonolite he scores for woodwinds, brass and strings against a guitar, bass and drums core, and the albums set his originals beside tunes such as "In a Mellow Tone", "Anthropology" and the Beatles' "I Want You". One original, "Song 315", recurs across While I'm Sleeping, My Heart Belongs to Daddy and Uzuraginu in different arrangements; he wrote it for Nakamure, and its title is the guitarist's birthday, 15 March. As an arranger for others he has written string parts for Aoba and horn parts for Otomo's orchestra.

He is a jazz musician first. The great majority of his credits are jazz, free jazz and improvised music, and his teaching and festival work sit in the jazz world. The edges are real but small: LowBlow's Mister Cafe is filed under rock and avant-garde by Discogs, Tipographica mixed jazz with progressive rock, and he has played bass on pop records by Morning Musume, Kahimi Karie, Carmen Maki and Aoba. Those are session credits beside the jazz catalogue, not a second identity.