Kara no Kyoukai 6: Boukyaku Rokuon (the Garden of sinners Chapter 6: Oblivion Recording)
Apprentice mage Azaka Kokutou, Mikiya’s younger sister, has been ordered by her mentor, Touko Aozaki, to investigate a certain incident in which fairies steal the memories of students at Azaka's school, Reien Academy. Azaka launches an investigation with the help of Shiki who can see fairies. As the investigation proceeds, Shiki finds out that Misaya Ouji, a student body president, is the one who controls fairies. However, the mastermind who gave her the power is Satsuki Kurogiri, a magus who controls words. Ironically, thanks to Satsuki’s magic, Shiki remembers that she had encountered Souren Araya and what he had told her two years ago.
[Source: Aniplex of America]