바이, 썸머 (Bye, Summer)

The song

‘바이, 썸머 (Bye, Summer)’ is a single by IU, released on 10 September 2025. It is a one-song release, and her first new song after the third remake album A flower bookmark, Pt. 3, which had come out four months earlier on 27 May.

The album introduction on Bugs carries a single line — “잘 가, 여름”, goodbye, summer — and a credits list, and nothing more. The lyric video was uploaded to the 이지금 [IU Official] channel a day earlier, on 9 September 2025. NME reported that the release came without any prior marketing or teasers and arrived with an animated video.

Reviews

IZM’s So Seung-geun reviewed the song on 23 September 2025 and began with why it exists. He reported that IU, having finished her world tour the previous summer, said she wrote the song in order to remember that happy, light feeling.

On the texture of the song, the same piece said that “this surprise single — dark, serious and heavy, and at the same time plaintive, like a Britpop band’s music — is a separate matter that has widened IU’s musical range”. So pointed to the “funk-style backing guitar” in the arrangement and closed by writing that “‘Bye, Summer’, in which the capacity IU has built up over a long time is at work, colours her palette in every shade”.

Around it

The song was sung on stage almost a year before it was released. NME reported that IU performed it for the first time on the opening night of two concerts at Seoul World Cup Stadium on 21 and 22 September 2024, the shows that closed her ‘HEREH’ world tour that year, and that she told the audience she had no plan to release it. So Seung-geun also noted that stage, writing that she played electric guitar on it herself.

The release followed about a year later, on 10 September 2025. NME described the song as a breezy, melodic tune set over soft-rock instrumentation of shimmering keys and electric guitars.