Cowboy Bebop is known for a lot of things. If someone were asked to say some trivia about it, some would probably make reference to its unforgettable soundtrack. Others would mention how Shinichirō Watanabe would go on to direct other great works like Samurai Champloo and Space Dandy. However, not many people would know that its manga adaption is classified as a shōjo.
According to Wikipedia, the Cowboy Bebop manga is actually a shōjo. Given what Cowboy Bebop is, it's difficult to imagine this series being targeted at young girls. This has led many to accuse Wikipedia of another case of publishing untrue, unbacked misinformation. However, MyAnimeList also classifies this series as a shōjo. Perhaps there really is something about the manga that would lead it to be classified as a shōjo. Getting to the bottom of this mystery will require a closer inspection of the facts.
First of all, it's important to understand just what a shōjo is. There's a common misconception that shōjo is a genre that involves a heavy romance element and is told from the perspective of the girl. However, shōjo refers specifically to a target audience of adolescent girls and young adult women; the genre can be anything from romance to action. This means that depending on how Cowboy Bebop is presented, it could still technically be classified as a shōjo.
The real issue is that Cowboy Bebop isn't just something that girls can enjoy. The anime's action, music, storytelling, and everything else that makes it great have universal appeal. It can be enjoyed by just about anybody.
In reality, Cowboy Bebop, the anime at least, would be better classified as a Seinen. For this demographic, the target audience is adults; it generally tackles more mature themes and complicated situations than most other anime. While Cowboy Bebop could certainly be enjoyed by younger boys and girls, its tone and content are best suited for adults.
With that said, the manga could be said to target younger audiences more than the anime. The art, facial expressions, and tone of the manga seem more typical of shōnen or shōjo anime. If any of these elements had been featured in the anime, they would have felt wildly out of place.
The art style is especially notable in the manga. Spike Spiegel, for instance, looks a little more like the bishōnen ("beautiful boy") characters typically seen in shōjo. Likewise, Faye Valentine looks a little more like a bishōjo ("beautiful girl") protagonist with her bigger eyes and detailed hair. If these characters with these designs had been placed in a bona fide shōjo wearing high school uniforms, they'd never feel out of place.
What truly makes this manga a shōjo, however, is the magazine it was published in. It originally ran in Monthly Asuka Fantasy DX. While this magazine ran anything from sci-fi to fantasy, it was primarily a shōjo manga magazine. Cowboy Bebop is considered a shōjo in the definitive sense because it ran in this magazine.
Of course, this wouldn't be the first time a seinen anime had its manga published in a shōjo manga. Darker Than Black, for example, is another seinen anime whose manga was published in Monthly Asuka. Just because a story is published in a magazine with a target demographic doesn't mean it can't appeal to broader audiences.
As for whether the Cowboy Bebop manga can truly be called shōjo by readers, that's still up for debate. The series, in general, has enough universal appeal that it could be marketed to just about any older demographic. If the manga happens to appeal to adolescent and young adult women, then that's okay, too.