Toyoshima Yasushi studied under Eto Toshiya and Angela Eto at the Toho Gakuen School of Music. While studying there, he began performing as a soloist on both the violin and viola, as well as performing chamber music and as a concertmaster.
In 1986, when he graduated from the college, Toyoshima was appointed concertmaster for the New Japan Philharmonic at the age of 22. He also served as concertmaster for the Saito Kinen Orchestra, Japan Virtuoso Symphony Orchestra and others. Toyoshima has earned a deep trust from conductors and orchestras. In 1997, with strong requests from the Kyushu Symphony Orchestra and New Japan Philharmonic, he became concertmaster for both orchestras, drawing much attention.
At present, Toyoshima is honorary concertmaster laureate of the New Japan Philharmonic and concertmaster laureate of the Kyushu Symphony Orchestra, concertmaster of the Hyogo Performing Arts Center Orchestra, and special honorary friendship concertmaster of the City of Kyoto Symphony Orchestra.
In recent years, he has performed as soloist in modern concertos by Erich Wolfgang Korngold, Miyoshi Akira and Bartók Béla Viktor János at regular orchestra concerts. In his 30th debut anniversary in 2016, Toyoshima held a highly rated concert with harpsichordist Nakano Shinichiro and performed baroque music pieces.
For two years from 2017 to 2018, he performed and conducted all of Mozart's violin concertos with the Osaka Symphony Orchestra, recorded live for a CD, which was well received. Toyoshima promoted his activities from the Kansai area as his base, such as concerts by the Alti String Quartet celebrating the 20th anniversary of its foundation in 2019 and performing all of Beethoven's violin sonatas with pianoforte. His new activities have drawn attention.
He displayed excellent performances with pianist Martha Argerich in Beppu, Oita Prefecture, Japan and Rome in Italy.
Toyoshima has served as concertmaster for the Saito Kinen Orchestra and Mito Chamber Orchestra based on a 30-year relationship of trust with conductor Ozawa Seiji. He has stepped in to successfully perform and conduct concerts when Ozawa could not conduct due to sudden illness several times. In December 2018, when Ozawa conducted for the first time in one year and two months in the Deutsche Grammophon 120th Anniversary Gala Concert at Suntory Hall, Toyoshima served as concertmaster.
In November 2019, he gave a series of three concerts performing all of Bach's violin pieces (six unaccompanied sonatas, six violin sonatas and six violin concertos) in Kyoto. For this achievement, Toyoshima received the Aoyama Prize at the 29th Aoyama Music Awards.
He is keen on educational activities, teaching at Kyoto City University of Arts, Ozawa Seiji Music Academy and Arkas Sasebo Junior Orchestra.
Toyoshima has released three CDs from Pony Canyon, and an album Tenderly that was recorded at Arkas Sasebo from Octavia Records. He has released many chamber music CDs from overseas labels that have been well received.
Toyoshima was the recipient of the Muramatsu Prize and the first Idemitsu Award in 1991 and the Cultural and Education Ministry's New Artist of the Year Award in 1992. He also received the 2013 Hyogo Prefecture Cultural Award. Toyoshima is professor at Kyoto City University of Arts and teaches at Toho Gakuen School of Music and its graduate school.