Iris

Appearance
From her portrait, Beel's mother seems to be a pretty woman with long black hair and gentle facial expression. She has no visible demonic features.

History
Little is known about her as of yet, other than that the Great Demon King painted a portrait of her. Out of embarrassment, he created an artificial demon to stop anyone from seeing it (despite it actually being quite good). Considering that both Beelze and his older brother En (who is very possibly also her son) constantly require wet nurses, Beel's mother might now be deceased. The Great Demon Lord instructed Hilda to become Beel's "mother", implying no one else at the time was able to fulfill that role.

Plot
Beel's mother's portrait, the "demon portrait", as it came to be known was requested by the Great Demon Lord to be retrieved by Hilda and her human companions. The painting itself was actually owned by Kugayama of St. Mark Academy, an acquaintance of Himekawa, who comments that the painting is of "a very pretty woman".