Kakkou no Iinazuke

A mismatched pair forced to get along for familial reasons, IN both anime MC has a crush and wants to convey his feelings to her, Also he is involved with other girls. If you love Harem Romcom, both shows are for you! 

Both are harem anime where the male protagonist has an initial crush on one of heroine but his parent engages him to another heroine for marriage. The male protagonist and the fiancee initially dislike each other but they grow closer with time spent together. Given the circumstance that the male protagonists are placed in, they will eventually have to choose whether to give their affection to their initial crush, new contrived fiancee, or any of the other romantic rivals. 

The premise of both: Faking being a couple to make their lives easier. There are different circumstances behind it (switched at birth vs. trying to prevent war from breaking out between yakuza families) but both start out as fake pairings, to become something more. 

Both deal with unwanted arranged marriages and the male protagonist liking another girl 

Very similar anime. The protagonist accidentally meets a girl and later has to play her boyfriend because of their familys. While the reason for the engagement in "A Cuckoo Couple" was a mix-up in the protagonist's birth, in "Nisekoi" it is the enmity of both yakuza families. Both are great romcom harem anime shows and well worth checking out. 

-both are harem anime with two characters being forced to be together -the main character is in love with a girl at the very beginning 

Not the plot but the general things you randomly choose looks similar. Like main characters nerd things and their motivations to study. Also I wanted to write it from Quintublet's side but this serie is airing new and in future it would be more sarcastic. 

- Harem Romance - Smart Protagonist teaches dumb girls. - Light hearted most of the time but has serious plot twists and such. - Rich vs Poor family  

Main characters are very similar, similarly paced character and harem development 

Main characters are very similar, isn't clear who he'll end up with. Cute girls that aren't boring (nino best girl) both mcs are a little dorky, love to study, and are absolute chads 

Unwillingly engaged couple with other love interests (mostly for the boy - harem). 

Both these animes revolve around the concept of arranged marriage where the ones that have been arranged are against the arrangement. The MCs, Yukari and Nagi are both attracted to a girl in their class and do not have an interest in indulging in an alternative relationship. At first, both arranged couples work together to prove they are not compatible but learn more and more about each other over time. Also, I really like how both Ririna and Erika look alike with the same hairstyle but are socially different.  

Both involve a phony relationship between two people who don't necessarily want to be together. Over time those feelings evolve. 

Both stories are about an MC that has a crush on a girl but becomes closer to another girl as a result of certain circumstances. Comedy and silly antics also play into both stories. The largest difference is the lack of good male characters in Kakkou no Iinazuke.