The Hypnagogia Grimoire is a grimoire book that appears in BlazBlue: Remix Heart. It has the power to enter a person's dream as they sleep. Depending on the victim's intentions, it can either cause incredibly enjoyable and happy dreams, or a living nightmare filled with the victim's worst fears, the latter usually surfacing if someone wanted to destroy the grimoire. If the person decides to stay in their dreams, he/she would abandon reality and never wake up. It can also bring drawings to life.
In the end, the grimoire got destroyed and vanished when Mai Natsume broke free from her despair.
- Mai Natsume - Mai's dream was that of having freedom and joy. However, the grimoire corrupted the dream, turning it into a nightmare:
- Mai's lives her father's rejection towards her, the latter calling her worthless and unneeded because of becoming a woman instead of turning back into a man.
- Mai manages to see her friends manically and savagingly killing each other for her sake.