People who know me will not find this to be a surprise.
After all, the most important woman in my life is one. I used to think light-hairs were the ones for me, but once more, even before reality, fiction showed me the error of my ideas.
The very first manga I ever consequently collected (and still consider a cornerstone to my and anyone's collection) is called 3x3 Eyes. A series that is very hard to define, as the scope & depth of the narrative shifts at several times over the course of its epic 40-volume run. Ultimately, its main appeal and the core of its being is the heart-warming relationship between Yakumo and Pai Ayanokuji. Their at times ambiguous relationship, though perhaps not the at the centre of the story, is at no moment forgotten by its hugely talented creator. The appeal of, on top of an intricately woven story-line (at times, it seems to me, even more intricately than originally envisioned) these identifiable characters in a thoroughly different world, was what made the series tick. And what made me come back for the full 40 volumes.
That, and Pai is a dark-haired girl.
Of course, at that time (well over a decade ago, people) I hadn't detected the pattern yet. Also, there was not all that much available as far as manga went. You kids now, you have it easy. Us old-timers, we had to work for our entertainment.
Anywho, the next series of note is the infamous, stunning and nigh-flawless Gunnm. First published as a 9 volume hard-core cyber-punk romp, following a strong-willed cyborg girl on her quest to find herself in a world that has completely lost its way, I litterly devoured it.
It was funny, intense & uncompromising.
Also, the main character, called Gally... A dark-hair.
Recently her story was continued, and, despite the long break between the original and Gunnm The Last Order, the energy (for me) is still very much there.
Still, in my defense, there's more to it than that. Motoko, for instance, the cyborg-bombshell of Ghost in the Shell fame, could never reel me in as others did. So (as I was sneakily trying to prove in the above examples) the story and more particularly, the characters' personality was what effected its planetary gravitational pull on me.
Finallly, the synthesis of sorts, is a French series, called Sillage. Its perky star, called Nävis, is the last scion of the human race, recovered from her home planet by the Galaxy spanning starship Convoy and enlisted as secret agent/spy on a ton of missions. Her stubborn character, her unbending will and her immediate visual appeal won me over faster than you can say: "raven-haired beauty".
Be seeing you
--nout