Prequel to BURN THE WITCH.

"Dragons"... from ancient times, they were considered fictional creatures, but they're not actually fictional, nor are they technically creatures. They are heteromorphic beings, and many of the deaths in London can be attributed to them. But most citizens in London don't know what dragons look like or know they even exist. Only those who live in Reverse London can see them. In Reverse London, there was an agency called Wing Bind (WB for short) that was in charge of protecting and managing the dragons. And there were two witches who belonged to Wing Bind...

(Source: Crunchyroll)