"Kōsui" (香水, lit. "Perfume") is a song by Japanese singer and songwriter Eito from his debut studio album, Sukkarakan (2021). The song was initially self-released for digital download and streaming on 21 April 2019 as the singer's debut single, and later released through A.S.A.B. "Kōsui" is an acoustic guitar-laid J-pop song, inspired by his experience of breakup.