Brynhildr in the Darkness Season 1 Episode 1

While I Wait For You

Murakami Ryota's best friend, Kuroneko, died in an accident trying to prove aliens existed when they were kids. Now, a girl who looks just like her transfers into his high school. When confronted Kuroha Neko insists she isn't Kuroneko, but she ends up revealing something else even more surprising...