KIRBY's enchanting R&B may be soaked in '60s and '70s nostalgia, but the narrative arc of Sis. He wasn't the one takes a decidedly modern bent. “Leon, Pt. 2” and “Break Her Heart for Me” depict the muddled feelings of being both the ex and the other woman, which the singer captures with elegant shamelessness. On “Boyz II Men”, she laments the immaturity of men who can't seem to grow up, noting that she's “too grown to be checking through your phone”. But when she teams up with BJ the Chicago Kid on the sensual “Lately”—a pairing delivered straight from the heavens—the sexual tension boils over. The album's leading lady is left in a sea of mixed emotions as the confident flirtation of the first half is replaced with a longing to fill the void with something real. “Wish I Loved” (as in “I wish I loved somebody that much or somebody loved me that much”) is mournful and hopeful in turns, while the clever “Blame the Internet” captures how breaking up in the digital era means being unable to escape an eternal sense of connectedness. KIRBY's juxtaposition of old-school soul with new-generation contours—and of undeniable vocal prowess with playful theatricality—gives her music the kind of singularity that puts her in a league all her own.