But first of all, since I'm sure many people here aren't familiar with this series, let's start out with some pictures. Here are two of the main characters of the series: which one do you think is East Asian?
Now, you may be thinking that's a little unfair asking you to work from just one closeup image with dim lighting, when actually reading a manga or watching an anime gives you so much more information to work with. Fair enough! Let's take a closer look at these two dangerous ladies, shall we?
This is Shenhua, who's an expert with swords and throwing knives:
She's originally from Taiwan, and is a freelance assassin/bodyguard who frequently works for a Chinese triad boss. As you can see here, she has a pale complexion, very dark gray/black eyes, and glossy straight blue-black hair. While she's occasionally been seen lounging at home in Western-style casualwear, her usual working uniform, shown here, includes a red-and-gold floral-patterned qipao. Her English (or in the original, Japanese standing in for characters speaking English) is good enough to be understandable, but has numerous grammatical quirks that show it's not her native language.
This is Rebecca, Revy for short, an expert gunslinger:
She's originally from New York City, and works as part of a small underworld courier/smuggler crew of expat Americans; one of their most frequent employers is a Russian mafiya boss. As you can see here, Revy has light golden-brown eyes, dark reddish/brownish hair that's straight to slightly wavy, and a light complexion that's a shade or two darker and warmer-toned than Shenhua's skin. Revy wears casual Western-style clothes -- her typical everyday uniform consists of a cropped tank top, cutoff jean shorts, and combat boots. Her English (or Japanese-in-place-of-English) has a native speaker's fluency.
Those images are screencaps I took from the anime DVDs, but the character designs are quite faithful to the manga originals:
And the accuracy of the adaptation extends even to the coloring of their hair, skin, and eyes. Revy's hair is the only area of slight inconsistency -- sometimes it's shown as dark brown, sometimes burgundy, sometimes dark reddish-brown -- but in any case the color art never shows her with cool-toned jet black hair like Shenhua.
The anime art in that first image above, and the manga color covers shown immediately below it, are clearly working with the same consistent physical design and color palettes, so this is obviously not a case where the anime version doesn't reflect the manga creator's original vision of the characters.
So, given all that information, what ethnicities do you think these characters are intended to portray? Which one is Asian?
It's a trick question -- they're both Asian! Shenhua is Taiwan-born Chinese, and Revy is Chinese-American. And creator Rei Hiroe clearly doesn't think that Revy's comparative lack of the most stereotypical ethnic markers makes her "look white". In the translated "Loser's Horizon" column reprinted in Black Lagoon Vol. 9, he explains his thought process in developing the character:
GX: (laughs) Since we've brought it up, let's talk more about the characters. What was your reason for making Revy a Chinese-American?
Hiroe: Ethnically, I wanted Revy to be a minority. And her look isn't Caucasoid, but rather Mongoloid. I thought that would make it easier for the Japanese readers to identify with her. Easier than if it was a white woman going ballistic. If she's a Chinese-American character, she may look Chinese, but her upbringing and her roots would be American. It's interesting when there's a gap between the way she looks and her way of thinking. People like that aren't really tied down to a region, like they're rootless wanderers. She's different from normal people so I thought she'd make for a more interesting character. And obviously, she probably faces discrimination in her life. Taking all that into account, I thought her character would stand out more.
("Normal" is such a loaded word, of course, but in this context I suspect Hiroe may be referring to people who are both ethnically and culturally part of the dominant majority group in their own country; he's consistent enough about writing numerous American POC characters that I don't believe he's coming from a place of assuming all Americans are white, or white = "normal".)
So, no matter how many Western fans out there think Revy "doesn't look Asian", Hiroe clearly doesn't see her that way at all, and his work reflects that; in the thoroughly multi-ethnic, multi-national world of Black Lagoon, where characters talk about (and insult) each other's race and nationality with great frequency, no one has ever said or done anything to indicate that they thought Revy or the numerous other Japanese and Chinese characters looked white. When ethnically-based teasing and insults are directed at these characters, they're all blatantly Asian-targetted references and slurs, not white ones. When Revy is in Japan for a job, she complains because locals keep expecting she must speak the language too, and are surprised and disbelieving when they learn she's an English-speaking foreigner, not Japanese (warning, some NSFW language in those scans.) All the pieces fit consistently with the sort of storytelling you'd expect if the mangaka is working from the assumption that these characters look Asian and expects his audience will see them the same way...just like Hiroe said he did. Funny how that works, eh?