AMX-114 Demeter is a machine used by the Haman Karn of Walpurgis.
The successor to the Qubeley. Just like the Qubeley’s name is derived from the mother goddess Cybele. Demeter is also a name derived from a mythological mother goddess.
Demeter’s mother Rhea actually was identified to be a form of Cybele by the Romans in ancient times. This is fitting, considering the fact that the Haman Karn of Walpurgis is likely her successor and well creation. (If she was made with Cloning, or Cyber Enhancements)
You can find this mobile suit in the on-going manga series, Mobile Suit Gundam Walpurgis