Japanese J-poppers SARD UNDERGROUND began life as a Zard cover band and paid homage to the '90s pop-rockers on their first album, Zard Tribute, released via Japan's Giza Studio in 2019. The LP reached number 24 on the country's Oricon Album Weekly Charts and stayed there for 10 weeks. Comprising Yua Shinno (vocals), Izumi Sugioka (bass guitar, backing vocals), Hiromi Sakamoto (keyboard, backing vocals), and former member Asaka Miyuu (guitarist) SARD UNDERGROUND launched their debut single in 2020, which marked the 29th anniversary of Zard's first single release, "Good-bye My Loneliness." "Sukoshi Zutsu Sukoshi Zutsu" was an unreleased cut written by Zard vocalist Izumi Sakai and composed by the band's long-time collaborator Aika Ohno. SARD UNDERGROUND's second single "Korekara no Kimi ni Kampai," also written by Izumi Sakai, was released in 2020 and was featured as the theme song for MBS's music television program +music. In May 2021, guitarist Miyuu Akasaka quit the band due to medical reasons. SARD UNDERGROUND unleashed their third tribute to Zard, Zard Tribute III, in 2022. A new J-pop single, "空っぽの心," also arrived that year.