Yoake Mae yori Ruriiro na: Crescent Love

An otherwise normal male protagonist thrown into the realm of royalty 

A girl from a noble family reunites with the guy she last saw eons ago as a child, and then hilarity and drama ensue. Both are those types of romance where the main couple gets decided quickly. 

Same story; difference is that one is serious is and the other is less serious. In both anime an alien princess comes to Earth and interacts with a male MC (and of couse fall in love) and several females around him (an imouto and osananajimi in both anime). Yoake Mae Yori is the serious one, UFO Princess is less serious (though it gets serious at the end). 

Both of these anime have a great romantic story line in which the two main characters form a unique and special bond. Also, both of the female leads are from high society but are down to earth and don't seem to care about social standing or wealth when it comes to the ones they love. 

Narue no Sekai and Brighter than a Dawning Blue both have a female character that aren't exactly from Earth and are very close to the main character. There is also an external conflict that tries to separate the two. Brighter than a Dawning Blue takes itself a bit more serious than Narue no Sekai which is more light hearted. 

princess from moon falling in love with a guy from earth. Very light hearted romance series with no love triangles or any sort of drama. Has good ratings from people under the review section  

Both of them have a couple that has different origins and try to go against the society to stay together 

A princess from the another planet visits Earth as a diplomat to try to ease tensions between the two planets after a war cuts ties of diplomacy between the two. The outerplanet inhabitants were originally earthlings that colonized said planets. The only trade-off is that you take away mecha action for a somewhat cheesy shoujo rom-com with closure. 

Both have cute characters designs and comedy elements. However, Yoake tends to be a lot of romantic. 

Both have similar comedy styles, are the same genre, and even share some plot points, such as having two characters from two different "worlds". 

Once again, there is the similar situation where the main male (at least, one of them) and female protagonists haven't seen in each in ages and the time that follows this reunion. Unlike Yoake Mae Yori Ruri Iro Na, Kimi-kiss ~ pure rouge includes a couple of love triangles that revolve around the two main male characters. Both have a very light heated feel that is fun to watch but include the flair of drama that adds a bit of a spin to the series. 

The situations of the characters are somewhat similar. After years of being apart, the male and female protagonists are reunited and realize that they are in love. Iin both cases, there is an obstacle that needs to be overcome before they can be together. 

both have a mysterious female main character, and both are about creatures coming from the moon, the two fall in love and people are trying to seperate them.  

Da Capo contains many girl characters that love the main male character in the way Feena loved Tatsuya in Yoake Mae. Da capo will seem shallow at first, but it actually gets pretty emotional near the end. If you like Feena, Da capo will feel like having many different Feena in one show, I guess.  

Yoake mae Yori ruri Iro Na (aka crescent love) wasn't linked to another, and I thought that it was such a fantastic romance that more people should find it. Similarities perhaps between the two would be loves from other "worlds", school. And a captivating love story. 

Both are romantic comedies with some addition of drama. Both protagonists are somehow not simple and have "special" parents. Both have Princess-type main heroines 

In both of these series the characters are very standard and are rather recycled. That's the first similarity I noticed. The second is how long it took for the main guy to admit his feelings for the main girl. Also, the main girls are so pretty! Both are laid back series and are generally a nice watch with storylines that aren't too intense ;3