Black★Rock Shooter (OVA)

Two similar pairs of girls become friends and end up fighting each other. Both have slice-of-life elements (far more so in BRS) and seem quite slow paced at the beginning. 

In both, two girls start off as pretty close friends and end up fighing against each other. In both, the friends who turn evil share the same name, Yomi. Both have dark music and nice fighting scenes. Both contain supernatural & slice of life elements but Ga-Rei Zero is much more tragic and dramatic. 

both protagonist are struggling with Yomi :D  

Both about a strong bond between girls, but they should fight each other against their will. In both one girl is ready to do anything to save other. But Ga-Rei is much more heartbreak. 

quite similar in the style of the story. 

In both shows we have two main heroines who become very close friends during the series and very fast but sadly in the end they become enemies who are forced to fight each other. Also how ironically it wouldn't sound, one of the heroines is called Yomi in both series and in both of them she ends up falling into darkness. The difference is that Ga-Rei Zero is much more dramatic and most importantly it gives a clear explanation of what is happening in comparison to Black★Rock Shooter. I definitely recommend to watch it. 

Both shows are about two best friends end up fighting each other. Another thing is that one of the main girl in both shows share the same name Yomi. The way the story flow is very similar. At first, it show two girls fighting scenes and then flash back to the point they first meet each other and how their relationship grow , how conflicts begin . After that it back to the fighting scenes to the end. 

Both have a storyline where the 2 main characters become very close friends but later one of them turns evil and the other one has to kill her. And coincidently in both animes the one that turns evil is a girl called Yomi 

Best friends who have to fight each other. In both shows those girls are very similar, one bright and full of life and always nice to others, not willing to hurt anyone, and the other serious and kind of noble, but because of this she doesn't have a lot of friends. They become very close, like sisters, but the second one eventually turns evil, and her friend has to make a very hard choice, not willing to fight her but being forced to. 

Both anime involves the beginning friendship of two girls but eventually turns into violent involving action, drama, and conflicts. Even two of these main characters in the series have identical first names. Friendship turns sour through unfortunate circumstances and their destinies intertwine in both series.  

You are a girl (a hot one) and you wanted to save your friend from something audience never get to know. But there are more than two girls in a show, and you can't get along with one without epic catfighting with the others. 1- Imagine yourself in that kind of situation, with physics-teaching alien who try to save the universe but lack the understanding of human emotion (aka. see human as disposable-condom-used-to-keep-the-excess-magical-power-used-to-save-universe-from-heat-death), and that alien is your employer. You got Magical Madoka. 2- Imagine yourself in that kind of situation in a black and white TV series that ended halfway and never announced sequel. You got BRS. read more 

These shows both have the same feeling. Also, both have middle school girls who end up fighting in "another world." Plus the animation is similar.  

'magical' girls, story about friendship and a hidden universe. When I watched the first ep, it hit me. This was like BRS, only more colorful and a lot darker[if that made sense] 

both have 2 worlds it seems, and gives off the same feeling and have really similar points in it. Both first start off with a dark scene, then introduce the characters with a light tone feeling, but gradgually gets darker. 

Though the plots of Magica and Black Star are different, the animation is basically the same way. If you love how Magica was drawn, you will love Black Star Shooter. Black Star also has a similar dark tragedy story like Magica, where its a female friend fighting for a female friend. It also involves alternate dimension like scenes. The only real difference is the two girls fight each other as opposed to Magica they fought 'witches' 

Both demonstrate the inner turmoil of schoolgirls as otherworldy combat. Both take their approach quite differently, but that twisted world is the one significant thing they share, and likely what you are looking for. Modoka Magica takes the route of magical girls who work toward squaring off against the inner evil of humanity. Only to be subject to the inner evil amongst themselves. As they come to learn of the twisted reality of the fate they have chosen, infighting occurs just before they face their greatest foe. Black Rock Shooter divides the world in two: the real world and the otherworld. In the otherworld you see girls squaring off in mortal combat, while in the real world these schoolgirls are living their normal lives. A jarring contrast until you find that the characters within each world looks like each other. read more 

Both are lighthearted and cute anime themed around friendship with well-written female characters. K-ON is a more classic slice of life, while Black Rock Shooter is more action and plot-based. 

Both feature anime girls doing battle in surreal, abstract settings. 

Both are about magical girls whose powers are themed around emotion. The Reflectors focus their emotions into their rings to transform, while the emotions of the girls in Black Rock Shooter become alternate personas in the mindscape. The main protagonist (Mato in BRS, Hiori in Blue Reflection) is a cheerful and pure-hearted girl, but is also forcing herself to be this way, and ends up carrying the burden of her friends’ negative feelings. Hiori trying to save her sister is similar to Mato trying to save Yomi. Both have a special element that carries emotions in humans. In BRS, it is an alternate persona, and in Blue Reflection, it is a crystallized flower called a Fragment. There’s even an alternate dimension that holds people’s emotions. The Otherworld (mental world) in Black Rock Shooter, and the Common in Blue Reflection Ray. Both worlds have their own unique style associated with them.  read more