Published in the US by Del Rey
Slugline: Resisting making the horn/horny puns here.
Raizo has a little problem in that he has a horn on his head, which makes the local villagers fear him and call him demonchild. It is that same deformity that marks him as the last scion of a noble house. Only four ninjas remain to protect Raizo from the enemies of his previously unknown ancestors so inevitably they bicker with each other over the best way to protect him and reestablish their house. The ninja fall into easily recognizable stereotypes such as the cross-dresser and the silent one, while as usual the bubbly one, here named Kagari, wants to get 'closer' to Raizo.
Scantily clad ninja girls protecting a younger hapless guy should be its own genre because I swear I have seen this plot before many times. The only question I have after reading the title is whether or not the ninja girls are color coded in the colored art of the series. Sure, some of the details are different such as what makes the male character 'special' which here is his horn. But the characters and the story itself are so familiar that I can feel the story beats coming by merely looking at the chapter heading art. While the manga by itself is well executed the manga itself doesn't yet offer anything interesting other than for collectors of fan-service as they marvel at the ridiculous situations created to give the fan-service a veneer of plausibility.
Ninja Girls, vol. 1 is also available from Right Stuf, Intl., an online retailer specializing in anime and manga.