The Asterisk War, Vol. 12 (light novel‪)‬

Family matters aren't so simple.
After confronting his father about Haruka, Ayato decides to visit Magnum Opus's lab to awaken his sister from the deep slumber she has been trapped in for several years. But the happy reunion lasts only so long, as Haruka tells Ayato of her past and her connection to Lamina Mortis. Meanwhile, realizing Haruka has been resurrected, the Golden Bough Alliance moves forward with their plan in the shadows...But first, Ayato will have to deal with Madiath's threats on both his life and Haruka's!