|Title||The Portal Demon|
|First Appearance||Alliance of the Golden Witch|
|Portrayed By||Yuki Kaida|
"I cannot bind anyone, and will not be bound. I don't want to be loved, I want to love."—Gaap, Alliance of the Golden Witch
Gaap (ガァプ Gaapu?) is a demon with the power of gaps, holes that can reach almost anywhere. She is very fashionable and up-to-date on the latest trends. One of the 72 Great Demons, the 33rd highest ranking earl of the underworld as well as Beatrice's friend.
Gaap appears as a young woman with ginger-blonde "drill" hair and blue eyes. She wears an elaborate red dress with black lacing and lined with white embellishments. She also wears a small red hat adorned with a pink bow. There are red bows on her neck and waist. She claims her dress is called "Jack the Ripper: Christmas Blood" from the Devilish Pretty collection.
- Gaap is based off of the demon Gaap from the Lesser Key of Solomon.
- Gaap is the only creation of Sayo's whose appearance is not based on a servant that Sayo worked with.