May not be suitable for minors (This is hentai after all. Adult stuff, not for minors!)
Karakuri Ninja Girl is one of those hentai series that don't really have a plot(which hentai does anyway?). But focuses on comedy instead. And that is what this show basicly is: A funny lighthearted erotic comedy about a couple who enjoys sex indoor and outdoor, being watched and just wanting to live their happy dream in the city.
"La Blue Girl" comes into mind, as it also has ninjas and sex in it. but don't worry. Karakuri Ninja Girl is not hardcore and does not feature tentacles or rape or anything
of that type. Karakuri Ninja Girl features boy on girl action and a bit of threesome and girl on girl action. The sex is creative, as the main characters are all ninjas, and have the ability cast various spells that enhances their actions. All from summoning a dildo to increases penetration speed and even turning a girl on. Breasts are shown in it's glory. But genitals are censored, or shown in unnatural forms as for example all shiny, black cloud or even a giant mushroom. There is no focus on the action "down there". But rather on the surface which helps with the comedy involved in the sex scenes.
As for visuals, it's early 90's quality. Kinda like Trigun. But the 90's animation quality is awesome for facial expressions which can be mad funny. And overall the art is good for it's time. Breasts and faces are nice to look at. Most hentai series don't have a high budget so quality tend to be low but for Karakuri Ninja Girl it is good. Bright colors provide a relaxed atmosphere and fits with the comedy focus of the series.
As for the sound and music. It's nothing special. You have the classical kunai throw, jump, slash, run, detection sound effects and the music in the background is oriental japanese inspired like those you would find in most ninja related stuff. The voice actors do their roles very well. Mika Kanai does a really good job as the voice for Suzuka(never thought she had voiced in a hentai, but it was great).
The characters are easy to recognise and unique for example Suzuka is blonde and Sagiri is red haired. Suzuka is a cute and childish character and Sagiri is more mature and adult, but still is a but childish. Tsukikage is your average simple minded hentai protagonist who enjoys girls and sex and overreacts to situations. The characters are simple but enjoyable to watch as they engange in various actions. Nothing deep or serious is involved with the characters.
All in all. Karakuri Ninja Girl is a funny, sexy vanilla hentai that makes fun of Sailor moon and focuses on comedy and sexyness rather than pleasure. Which means it does not focus on a certain fetish/fetishes. There is no tentacles, rape, torture etc. Breats are shown but genitals are censored. It's an erotic comedy with bright colors and characters which gives you a relaxed feeling with no worries about what may happen next. It's a good watch but with its shortness of 2 episodes only do not expect a great story plot with amazing twists. This is hentai. And a funny one it is! This is a great watch which will make you laugh, if not, giggle at least!