Injuu Gakuen La Blue Girl

Both series have a plot with ninjas and sex. La Blue Girl is more hardcore with tentacles, demons, rape and so on. Both series have a "old school" anime style to it. Ninpou Midare Karakuri is a hentai/softporn which focuses on vanilla sex, public sex and comedy. It has the normal boyxgirl thing. With a little twist of ninja spells, potions and threesome to add some flavour to the sex. 

Monsters having sex with women. 

both have very perverted humor, sex, yuri, and ninjas. 

Both can be hailed as tentacle hentai classics. La Blue Girl is more on the fantasy side of things with weirder monsters, magic, and things like that with actually quite a focus on comedy. Twin Angels takes itself a little more seriously and has a similar setup with demons and magic, but dishes out the comedy for a little more action and violence. If you're in the mood for some older tentacle hentai, these are both worth checking out. 

Both are based on manga from Toshio Maeda. The main protagonist in both anime is fighting against demons from another parallel dimension that threatens mankind. They are also both action-packed anime with similar animation and a similar vibe. Urotsukidoji: Legend of the Overfiend and LA Blue Girl both contain similar levels of graphic scenes of violence, blood, gore, sex, nudity and tentacle rape. The main difference between the two anime is that LA Blue Girl is more comedic, while Urotsukidoji: Legend of the Overfiend is darker and serious. If you like one, you should enjoy the other.  

In many ways, these anime are like night and day, but they also have much in common. Your main hero is a female with superpowers (Miko = demons, Rika = angels), and she fights lots of tentacle monsters. Neither are exactly modern masterpieces of anime, but if you're looking for an ecchi anime to add to your collection, and you liked either of these, you will very likely enjoy the other. 

Both are erotic anime starring an attractive blue haired girl who is the successor of a skilled warrior clan. Both girls have a sidekick who pervs on them (Kaede and Nin-Nin) for comic relief. La Blue Girl is straight up hentai and while Manyuu Hikenchou has sexual situations it only shows boobs. Tons of them, though. I think if you like one you would like the other for sure. 

Miko Mido is back in the continuation of her story. Same hentai antics with demons and tentacles and ninja sex-craft.