They are used by both Yuuri and the Soujus from the beginning of the story, but their origins remain unknown until much later. The witches created by them can be detected only by Kazumi's ahoge. Unlike conventional Grief Seeds, Incubators cannot consume them. They apparently do not activate on their own like Grief Seeds, but must be inserted into a host via the forehead by a magical girl.
In Chapter 18, it is revealed that the Evil Nuts were created (and distributed to Yuuri and the Soujus) by Kanna Hijiri. They are a combination of Umika Misaki's analysis magic and Niko Kanna's regeneration magic.
Women affected by the Evil Nuts:
- The preying mantis witch, created by Yuuri inserting an Evil Nut into a policewoman named Misako Ishijima. She turned into a giant bug-like creature and attacked Kazumi when she figured out that Ishijima had framed Tachibana for a bombing.
- The cosmetics witch, created by Yuuri inserting an Evil Nut into a cosmetics saleswoman named Kyouka Shida. She battled Kazumi, Umika and Kaoru after attacking girls who were using dark, unhealthy makeup.
- Kazumi, a magical girl who gained sharper teeth, unusual pupils and greater strength. Her hands and feet transformed into long, claw-like appendages. Kazumi temporarily lost her mind and became animalistic during this time. This effect is unique to Kazumi, as she was already a witch (albeit in a human body). Regular magical girls become full witches when affected by Evil Nuts.
- Saki Asami, a magical girl. Her Soul Gem broke open and she became a regular witch.