Testset has been played on NTS shows including Iglew, with Splintered first played on 24 February 2016.

FUJI ROCK FESTIVAL ‘21にMETAFIVEの特別編成として出演した砂原良徳とLEO今井が、GREAT3の白根賢一（Dr）と相対性理論の永井聖一（Gr）を迎え、グループ名を新たにTESTSET（テストセット）と冠してライブ活動を開始。2022年に1st EP「EP1 TSTST」配信リリースし、SONIC MANIA、朝霧JAMなどに出演。2023年、1st Album『1STST』をリリースし、FUJI ROCK FESTIVAL ‘23に出演後、初のワンマンライブ「TESTSET LIVE 2023」を恵比寿ガーデンホールにて開催。2024年夏、デジタル・シングル「Sing City」をリリース後、SONICMANIAへ出演。10月20日（日）ワンマンライブ「TESTSET 2024」を開催する。

In 2021, Yoshinori Sunahara and Leo Imai played FUJI ROCK FESTIVAL as an emergency one-off lineup of METAFIVE, with Kenichi Shirane (GREAT3) on drums and Seiichi Nagai (Soutaiseiriron) on guitar. This four-piece subsequently changed their name to TESTSET. In 2022, they released their first EP ‘EP1 TSTST’ and played a series of shows and festivals, including SONICMANIA and ASAGIRI JAM. In 2023, they released their first album ‘1STST’ 2023, played FUJI ROCK FESTIVAL, and held their first full show TESTSET LIVE 2023 at Ebisu Garden Hall. In 2024, they released a digital single 'Sing City', followed by a performance at SONICMANIA. Their upcoming show TESTSET LIVE 2024 will be held on October 20th at Zepp Shinjuku.