Ore no Imouto ga Konnani Kawaii Wake ga Nai.

Same writer, same story. 

-both series got the same incest, although Yosuga no Sora is a bit more "intense" in the term of it. -both series have a pseudo-harem on it 

Both are the second season, where the male character is surrounded by several females all the time. Both go into some character devolepment (though not very much). There is a similar rivalry between the 2 main female leads: Yozora/Sena and Kuroneko/Kirino. 

Both anime are about the brother and sister relationship. The difference between these two is that the sister in OniAi she show her love and care towards his brother and the anime show how she is deeply inlove with his brother while oreimo 2 the sister is a tsundere toward his brother.  

Both Mahiro & Kyousuke will do anything for their loving sister. Both Mahiro & Kyousuke will give up everything for their loving sister. The difference between the two: Oreimo 2 is about the brother and sister relationship while Zetsuen no Tempest is about finding the Killer of Mahiro's sister, Cause the big question in these anime is WHO MURDERED MAHIRO'S SISTER? 

Both anime are about the brother and sister relationship. The difference between these two is that My Little Sister Is Among Them! the brother is trying to find his sister while oreimo 2 is more on hanging out with your sister playing eroge games.  

Both anime have a plot of brother and sister falling in love to each other. Both brothers in these anime will do anything for their loving sister. Both brothers in these anime will give up everything for their loving sister. Both brothers in these anime are helping their sisters to achieve their goals in life. Both brothers in these anime are helping their sisters to find friends. The difference between the two is: sasami-san@Ganbaranai is a supernatural anime about Gods while Oreimo 2 is more focus on having a good time with your sister, playing eroge games.  

Both anime are about the love story of a brother and sister relationship. The difference between the two: Oreimo 2 is a Harem while Kuro to Kin no Hirakanai Kagi is a Reverse Harem. 

Frustrating as hell. Entertaining as hell. Moving as hell. Top class anime, both. 

Similarities: - The siblings relationship of both series are intensive - A harem full of beautiful girl - School settings - Both oniichan are voiced by Nakamura Yuuichi. If you're interested in seiyuu, there's a bunch of exciting things you can find out yourself Differences: - Behaviors of the little sister - Mahouka deals with more serious subjects, Oreimo mainly focuses on daily life problems 

Both Hiroomi & Kyousuke will do anything for their loving sister. Both Hiroomi & Kyousuke will give up everything for their loving sister. Both Hiroomi & Kyousuke are helping their sisters to achieve their goals. Both Hiroomi & Kyousuke are always their for their sister if Mitsuki nor kirino are in trouble. 

Both sister in these anime love their "brothers". Both anime are about making friends and both anime show how can you become closer with siblings.  

Both anime have the brother and sister relationship and both sister's in these anime was voiced by Taketatsu Ayana. The difference between these two anime is that date a live is about dating a girl with supernatural elements while oreimo 2 is more on hanging out with your sister playing eroge games.  

Both anime have the brother and sister relationship. The difference between these two is that kiss x sis is more on ecchi and doing stuff with your sister while oreimo 2 is more on hanging out with your sister playing eroge games. 

if you love romance between a brother and a sister then you should watch both of these anime. 

Both anime about brother and sister relationships. The difference between the two: Oreimo 2 is a romantic comedy while Hitsuji no Uta is a psychological anime. 

Both anime include social outcast (sorta) female leads with otaku hobbies that are trying to fit into normal society. Both anime also include the older/younger brother helping their sisters to cope with their problems. Both anime have similar mood, although Oreimo is slightly more romance focused and Watamote focus slightly more on the social issues.  

The same situation where they male character never gets any respect from the main female character, except in one anime it was the guy himself who made his sister hate him, while the other one the female lead was a tsundere to begin with. 

Both anime have the brother and sister relationship. The difference between these two is that the sister in canvas 2 she show her love and care towards his brother and the anime show how she is deeply inlove with his brother while oreimo 2 the sister is a tsundere toward his brother. 

Both anime have the brother and sister relationship. The difference between these two is that boku wa imouto ni koi wo suru is a serious drama about falling in love with your sister while oreimo 2 is also about falling in love with your sister but with humor and more on playing eroge games with your sister. 

Both anime have the brother and sister relationship. The difference between these two is that kiss x sis is more on ecchi and doing stuff with your sister while oreimo 2 is more on hanging out with your sister playing eroge games. 

They both have characters that love their little sisters too much 

Both anime are about the love story of a brother and sister relationship. 

Both anime are about the brother and sister relationship.