Initially released for digital download and streaming only, the physical CD was included in the DVD/Blu-ray box set of the documentary Pieces: 29th Winter, which was published on March 23, 2022.

[4] The disc collects five acoustic and orchestral songs, entirely in Korean, written, composed, arranged and produced by IU over the years, performed at concerts and events with fans,[5] but never released, and which represent "pieces" of her twenties.

[5] "You" was written at 24 during a few days' stay in the mountains to shoot Moon Lovers: Scarlet Heart Ryeo,[5] and talks about missing her upstairs resident friend, actress Yoo In-na.

[8][10] The lyrics were written as a love letter left by an elderly person to their partner before dying,[5] and the last verse, "More than anywhere else, I'll stay inside you" (Korean: 어디보다 그대 안에 나 머물러 있다오), was the starting point for "Epilogue", the final song in IU's fifth album, Lilac.

"[16] Reviewing for Newsis, Lee Jae-hoon felt that the sincerity of the lyrics and the production, which managed to "organically weave together tracks that were pieces in their own right," had "painted the scenery of a song that was lost in time.

He concluded his review by writing, "The reason this collection deserves to be valued higher is for IU's ability to sublimate her seniors' magnetism, whom she has been influenced by, into her own personality.