Here is the painting for this episode.
WARNING! THE REST OF THE POST CONTAINS SPOILERS! ABANDON ALL HOPE YE WHO ENTER!
And here’s the OP video.
Many people speculate the man in blue suit is ‘Wizard-Hunting’ Wright who was mentioned in ep 5 considering he has the same eyes, theme color, and insignia as ‘Death Sentence’ Dlanor. Regarding the person in red suit, it’s still a debate whether s/he is a male or a female. Some theorizes s/he is Jessica or someone connected to her (or perhaps Natsuhi’s lost son) and some considers Wright’s lover who mar or may not be male thus adding another bromolust element to our murder mystery (because Günther-like demon butler and a crossdressing shipper demon are never enough).
But these all are just theories and only time and Ryukishi07 know will tell.
PS: Seems Bern will play a huge role considering the OP. The Bern fanboy within me is happy now.