Eight years into his idol career, NCT's Jae Hyun finally gets the opportunity to showcase his own musicality through his solo debut. Jae Hyun, the "valentine boy" who was born on Valentine's Day, delves into love in the eight-track R&B-infused pop album J.

"Hold up you're too hot too hot, smoke coming out the boombox." Jae Hyun falls into a hot romance in the title track Smoke (Track 1). The hip-hop R&B plug gives off groovy vibes that listeners can easily ride on, and an alluring ambience with the romantic lyrics and Jae Hyun's mumble singing at times. The English version (Track 8) of Smoke serves as the closing track of the album.

Before the release of J, Jae Hyun first teased the two pre-release singles Roses (Track 2) and Dandelion (Track 4), which totally raised anticipation for the whole record! He expresses how Roses trigger memories of a past lover in the intense and heart-wrenching R&B song: "It's killing me to know there's someone else out there buying you / Roses (roses), roses yeah, (roses) / I'm triggered every year Valentines / Don't wanna see no." In the mid-tempo R&B Dandelion, he shares a love like a blooming dandelion in the shining sky.

Besides writing lyrics for some of the tracks, Jae Hyun also works as the primary composer of Flamin' Hot Lemon (Track 3). Inspired by a Flamin' Hot Lemon-flavored snack, the R&B tune shows his appreciation for the different traits of his crush. Calm and sorrowful ballad Completely (Track 5) comes with beautiful lyrics in a minimal, peaceful piano and strings melody. He gets confused about love in the R&B number Easy (Track 6), and sweetly confesses about a special person who lingers in his mind in the mid-tempo R&B Can't Get You (Track 7).