- The One
- Digital Single
- Gu Family Book OST Part.6 (구가의 서 OST Part.6)
- Jal Issnayo (잘 있나요; Best Wishes to You)
- Jal Issnayo (Inst.) (잘 있나요)
"Gu Family Book OST Part.6" is the ninth digital single released by The One. The song was used as the theme song for the drama Gu Family Book, and was later released on its OST.