Reinforce(リインフォースRiinfōsu) is a key character in Magical Girl Lyrical Nanoha A's, who reveals herself near the end. She does not appear in either Magical Girl Lyrical Nanoha or the alternate universe shown in the Triangle Heart series. She is voiced by Sanae Kobayashi. The former Book of Darkness and creator of the Wolkenritter (Signum, Vita, Shamal and Zafira), Reinforce was reformed by Hayate Yagami and became her partner.