randomness, a bit of ecchi and a lot of weird humour, both Haiyore Nyaruko-San and Plastic Nee-San are very much alike in genres, but they are totally different in scenery, if you like this kind of humour, you will like both animes for sure
Koushi Inuzuka wants to be a prosecutor. He has excellent grades, good morals and is very popular. However, his father is a talented martial artist who wants Koushi to follow in his footsteps, and he is hiding an important secret! When Koushi was younger, he was betrothed to the daughter of his father’s rival: Momoko, the strongest bride in the world! She’s cute, devoted, and a talented martial artist; and with Koushi’s father’s blessing, she is now the newest member of the Inuzuka household – much to Koushi’s dismay! Now, all Koushi wants to do is live a normal life and become a great prosecutor… but with two martial artists to deal with, can he keep his path – and sanity – intact?
Both revolve around an OP chick that loves fighting has a major crush on the relatively normal MC, whom they are protecting. Crush is completely unrequited by said MC, who will use force to prevent the frequent sexual advances. Both of the females are very quirky and often do irrational things, causing their crush to act coldly towards them. Also worthy of note is the fact the both male MC's have side characters that like them too. The setting is different, but both anime have a lot of specific things in common.
The eccentric Suzumiya Haruhi wants nothing more than to meet aliens, time travelers and espers… but she’ll have to settle for the everyday Kyon instead! Along with the mysterious Itsuki and the vacant Mikuru, the duo forms the SOS Brigade – a club whose mission is to discover the mysteries of the world. Armed with a razor sharp wit and a skill for manipulation, Haruhi will stop at nothing to have fun at all costs, even at the expense of Mikuru’s dignity!
If you like shows were a normal human boy is dragged away from his nice, quiet life by an assorted mix of unusual creatures, such as aliens, you're in luck. Both Nyarko-san and Haruhi features genre savy characters, deity/human relationships and a plot mixing humour and romance. Furthermore, Nyarko-san references Haruhi on several occations, so having watched Haruhi actually enchances the experience gained from Nyarko-san.