Toshiki Nagata (永田利樹, Nagata Toshiki in Japanese name order) is a Tokyo bassist and composer, born in the city on 6 September 1959. His own biography says he graduated from Rikkyo University, where he studied law, and then trained as a bass player: classical double bass technique with Keizo Mizoiri, and jazz technique and theory with Gary Peacock. It lists sessions and recordings with a long run of Japanese players, among them Yosuke Yamashita, Shuichi "Ponta" Murakami, Kazutoki Umezu, Fumio Itabashi and Takehiro Honda.

The thread that runs through his career is the saxophonist Sachi Hayasaka, who is also his wife. He is the bassist on her debut as a leader, Free Fight (Mobys, 1988), recorded in Tokyo in November 1987 and January 1988, and Discogs credits him as the composer of two of its tracks, "Monster's Teardrops" and "Nbagi". He stayed through the Stir Up! records that followed, including the live 2.26 (Enja, 1994), recorded at the Tokyo club Buddy on 26 February 1992 with Yamashita as guest pianist, and Milagros (Off Note, 1996). By the late 1990s he was also co-producing her records: Discogs lists him as a producer on Milagros, Double Rainbow (1998, recorded in Brooklyn), Beat Beat Jazz Beat! (2005) and the percussion-led group Minga's Palpitante! (2008). His biography places Stir Up! at the Moers festival in Germany and the Ost West Festival in Nuremberg in the 1990s, and says he also worked in New York, at the Knitting Factory and SOB, with the drummer Pheeroan akLaff, the trumpeter Wadada Leo Smith and the trombonist Josh Roseman.

A second long-running home is the pianist Satoko Fujii's Tokyo orchestra. He is the bassist in her sextet on Past Life (Libra, recorded 14 April 1998) and in the Tokyo half of the two-disc Double Take (EWE, 2000), recorded at Okegawa on 27 October 1999 and paired with her New York orchestra. He then appears on Before the Dawn, taped at the Yamaha Jazz Festival in Hamamatsu on 16 June 2002, on Live!! (recorded at Pit Inn, Shinjuku, in 2005), on Zakopane (2010), and on the two tribute records Peace (2016) and Kikoeru (2018), both recorded at Buddy. The trumpeter Natsuki Tamura is on every one of those dates, and the saxophonist Hiroaki Katayama and the trombonist Hiroshi Fukumura are on the ones where Discogs lists them, Double Take and Before the Dawn.

His own name goes on the front of fewer records. Ecdysis (Nbagi Record N-003, 2000) is his first album as a leader: recorded at GOK Sound on 2 and 3 February 2000, with Natsuki Kido on guitar, Eiichi Hayashi on saxophone, Akihisa Tsuboy on violin, Yasuhiro Yoshigaki on drums and Tobby Suzaki on percussion, Hayasaka as executive producer, and Nagata credited with bass, vocals, the music, the production and the cover painting. Its tracks include "Lucifer's Bebop", which Hayasaka's Milagros had already used, and "Ghost in the Clave", which he came back to on the Baila TReS records. In 2009 he and Hayasaka were billed together on East Village Tales, a live set recorded in New York with Pheeroan akLaff on drums and Shiro Sadamura on electric violin. In 2016 Bummey Records pressed 100 hand-numbered vinyl copies of Desireless, a live record of the contrabass players Takashi Seo, Naoji Kondo and Nagata, taped at the Kichijoji room Sound dzumi on 26 June 2015.

Outside jazz-club settings he has been an adaptable sideman. Discogs credits him on Dub Jazz Jazz Dub (2009), a Tokyo record by the British reggae producer Dennis Bovell's jazz band, accompanied by MAU, the group Nagata formed; on Jazz Nino (2004), where Minga meets the hip-hop group Think Tank; on Tomohiro Yahiro & Os Amarelos (2004); on the singer-songwriter Masaru Watanabe's records; and on the 2021 Itiberê Zwarg Orquestra Família do Japão, where he is credited on acoustic bass. His biography says he was bassist in the drummer Pheeroan akLaff's Japan-tour unit from 2012 to 2014, and he plays on akLaff's Dear Freedom Suite / Live in Japan Volume 1 (ModernMasters, 2013).

Since 2012 his main group has been TReS, the family trio of Hayasaka on alto and soprano saxophone, Nagata on bass, and their son RIO (born in Tokyo on 24 May 1993) on baritone saxophone. The name is Spanish for "three" and also carries the members' initials. The trio was put together in June 2012 for concerts in Argentina and has since recorded Escualo (2013, a tribute to Astor Piazzolla), La Luna Roja and Viento Apasionado. The group says it played the Buenos Aires International Jazz Festival in 2014 as the first Japanese group invited, took part in the Earshot Jazz Festival in Seattle and the International Jazz Festival in Havana in 2016, and toured about 60 venues across Japan in 2017. With the pianist Shiko Ito and the percussionist Gen Ogimi it becomes Baila TReS (and, with Ogimi's son Umi on drums, Baila TReS / Dos Familias+), which has released Baila TReS (2019), Eternal Blue (2022), Nue and Desertification (both 2025, taken from a set at Pit Inn on 25 September 2024). He also plays in Hayasaka's sextet MG6, whose Live at Pit Inn (2024) was recorded on 2 September 2023.

TReS is billed as Sachi Hayasaka / TReS on the Barbican Hall programme "Haruki Murakami's Jazz at Peter Cat: a Japanese Jazz Night", part of the EFG London Jazz Festival, on 21 and 22 November 2026, on a bill with Junko Onishi's trio.

Nagata plays acoustic double bass for most of his work and electric bass when the setting calls for it (he is credited on electric bass on the Tokyo disc of Double Take). His training is two-sided, classical technique from Mizoiri and jazz from Peacock, and his bio adds tango as a third influence. The records show the spread: the free-leaning big-band writing of Fujii's orchestra, Hayasaka's Stir Up! bands and her percussion ensemble Minga with the Senegalese sabar master Wagane Ndiaye Rose, Piazzolla's tango repertoire in TReS, Brazilian music with Yahiro, and dub and hip-hop dates with Bovell and Think Tank.

He is also a composer. Besides the Free Fight pieces, Discogs credits him as writer of "Nimba" and "Lucifer's Bebop" (both on Viento Apasionado and on MG6's Live at Pit Inn) and of "Ghost on the Clave" (on Eternal Blue and Nue), and he has written for television and film, according to his biography. The shape of his playing is that of a bass voice that often leads a front line of saxophones: in TReS two saxophones and a bass are the entire band, which leaves the bass to carry harmony, pulse and counter-melody at once.