Lee Hyori is releasing a new song after a long hiatus.

On January 28 at 6 p.m. KST, Lee Hyori will drop her new single "Heart, Firm as Ice" on major music platforms. The track is part of lyricist and music producer Park Chang Hak's long-running Songbook Project.

Label team Cabeto explained that Lee Hyori personally expressed her intention to participate, which led to the project's launch. She was actively involved in both song selection and interpretation.

The team highlighted her distinctive vocal color, noting that Lee Hyori delivers a restrained yet mature performance built around a cool, resolute emotional core.

The song is driven by piano and string orchestra arrangements, creating a deep, lingering resonance. Singer-songwriter Jeon Jin Hee handled the main arrangement, while Lee Ji An was responsible for the string arrangement.

This release marks the fifth single from Ode to Love Songs: Park Chang Hak Songbook Project, a series that reflects on Park Chang Hak's 35-year musical journey.

The track is a newly arranged version of a song originally released in 2011 on saxophonist and composer Son Sung Jae's album Rain of Rain. The original version was sung by Jo Won Sun of Rollercoaster.