When All Else Fails [Destroy It All] (Mephisto/OC)

The ‘angel of hostility’ is back in the Japan Branch after many years. Her close relationship with the King of Space and Time has always been suspicious to the Order, but it was her friendship with Shiro that kept her on good terms. And she’s one of the few that knew of Satan’s half-demon son, the one who inherited the blue flames. She now comes back to have some fun.

(Set during manga, not anime)