Noire is a consistently popular member of the Neptunia cast, and for a variety of reasons.
For one, she personifies the range of consoles that have, to date at the time of writing, played exclusive host to the games in the series: Sony’s PlayStation 3 and PlayStation 4, with her younger sister Uni representing Sony handhelds the PSP and Vita. As such, it’s natural for people to feel drawn to her — though quite a fun little twist in the fact that she’s not the franchise’s main character.
For another, she embodies the enduringly popular character trope of the tsundere; that hard-shelled, soft-centred sort of person who puts up an abrasive, sometimes aggressive front but actually just wants to be liked or even loved.