The Ekimmu, also known as the Edimmu, are a type of evil Utukkus from Akkadian and Sumerian lore. They were envisioned as the ghosts of those not buried the right way. They were considered vengeful towards the living and would possess those who broke taboos.
They were thought to cause disease and inspire criminal behavior in the living and were considered nearly incorporeal wind spirits that sucked the life out of the susceptible and the sleeping (most commonly the young). It is also said that they could sometimes be appeased by funeral repasts or libations.
Edimmu appears as a miniboss in Nakano's Stone Site silver level instance, Ueno's Mirage instance, and part of the Lord of the Flies series of quests. The ability to fuse him is acquired through completing tasks for the master of the cathedral in Shinjuku Babel. He's a special fusion of Raijuu and Jinn.