It's hard to say that the harem comedy sub-genre needs a shot in the arm since they have such a low ceiling in terms of innovation, so the key to having a successful title is to just have fun with it, and that's what Ninja Girls does well. It's far from original and does everything you've already seen before, but this is the most fun I've had reading this type of manga in years.
Story 7: Raizo is a down-on-his-luck boy who is the remaining member of his fallen family, and in an attempt to restore his family hierarchey (I think I butchered that),
he must marry into a wealthy family with the aid of three kunoichi who unintentionally make his task that much harder. Generally, I'm left with the impression that in these types of stories, male lead and female lead will end up together and everything else in the middle is just filler, and I'm sure other readers of this manga can see the same writing on the wall, but I'll be a bit honest, I probably would've been okay with any of the candidates introduced here. Each volume of the manga follows one viable young girl whom Raizo must "trick" into marrying him, each girl's story is very good and well thought out for several chapters to a full volume. They aren't just here for eye candy, even though they are all easy on the eyes, but I'm amazed at how not only each girls' tale plays out (it IS pretty formulaic, yet effective), but Raizo's genuine concern and willingness to help touches each bride-to-be's heart, cumulating to playing a role in the final chapters. Ninja Girls' secondary plot involves of course the impending romance between Raizo and Kagari that may not be subtle, but it's a slow build I was anticipating to see how far the limits of loyalty and love will be stretched. Okay, that might be a bit hyperbole, but this is just how caught up in the fiction I got with this manga and a testament to how much fun I was having that a story this run-of-the-mill and predictable had me going. Simple, yet satisfying.
ART 8: A knock against Ninja Girls is that the manga isn't fleshy enough, and it maybe tame in comparison to Samurai Harem or Omamari Himari, but for my tastes, I'm perfectly fine with this title not making it a booby-revealing oogle-fest like the formerly mentioned as it's bread and butter. That sort of transperent style sets comedy back a decade. Make no mistake, the ladies in Ninja Girls look very spicy and the partial nudity is handled very tastefully as opposed to blatant exposure for the sake of it. Nothing wrong with being a little titillated, what fun would Christmas be if you present wasn't wrapped?
Fight scenes are beautifully drawn and black levels are done really well, no action-based panel looks like a cluttered mess. I would say that it's on par with A Certain Scientific Railgun. Character facials are another huge plus, this manga doesn't rely on constantly using superdeformed comedy gags and follows Gintama a little more closely with it's physical satire. Even when some of the more dramatic moments, the characters' "acting" is top notch, especially Kagari. The atmosphere of feudal Japan are done very nicely, but few and far in between, since the characters take up most of the panels.
CHARACTERS 7: The cast really hits home here, and also nails another important factor for a good harem comedy: how many girls are too many? I enjoyed Rosario+Vampire until Mizore and Moka's little sister were introduced and Nejima has up to 30 different girls all vying for page time, which renders character development protracted and tedious. Ninja Girls is focused on mainly Raizo and his interactions with kunoichi Kisabi, Kagari, and Himemaru and the highlighted bride for each respective volume. Because of the relatively small cast of ladies, this keeps characters from being limited to one note gags and in the 9 volumes total, does a good job of fleshing out each of them. Raizo himself is every bumbling male lead in a title of this nature, and like most, he's a pretty likeable chap. If anything, he's probably better than the likes of Keitaro in Love Hina or Yamato in Suzuka, due to the degree of his task and the bond he shares with his tribe of gals. Also, his big heart is a major plus, as he never feels he can fake being a Casanova and his sincerity is genuine. Raizo isn't presented as a hopeless loser who just falls into a pair of huge, gravity-defying breasts all the time, nor are any of the kunoichi purposely torturing him just out of sick pleasure in the hopes that the reader will find this funny. The ratio of assistance/pain is pretty close to how the Tenchi franchise balanced this formula with Ryoko and Aieka, minus the romantic implications. In attempts to ease Raizo's suffering, their hearts get ahead of their brains and make the situation worse. This is easy stuff, yet authors are more prone to write sadistic comedy like Bludgeoning Angel Dokuro-Chan and Tora Dora, where the female lead is so hair-trigger angry and violent towards the protagonist that the creators must think I'm some kind of idiot to hope she winds up with the guy by the end of the story. I'm not biting.
Ninja Girls' only weakness is probably the villians. Kabuki Seigan isn't a terrible bad guy, he just can't be taken seriously because he comes off more like a high school jock that's jealous of the nerd kid whose friends with the hottest girl in the class. I suppose for a tongue-in-cheek comedy, it's effective, but he should've been made funnier instead of making him imposing near the end, where he barely did anything. His two henchmen were more impressive and legitimately funny, easily outshining your top heel in the story.
OVERALL SCORE 8: Ninja Girls is a fun read that's a nice change of pace from other harem titles with it's throwback comedy, lovable cast of wacky personalities, and lovely artwork. If you're looking for gratuitous fan service, this probably won't do the trick, but if you overlook that little nit pick, you'll find a harmless, entertaining story that's character driven. It's short length also keeps it from getting tiresome.