Blitzo won't do too bad because he does speak English. I don't think he speaks anything else because he doesn't have a great education and we only see him doing business with Sinners who would have spoken English
And I don't think all demons speak all languages in this universe since only Crimson seemed to notice that Fizz was singing gibberish when he started just singing a bunch of random Italian foods
Remind your Japanese speaking Dominant that he needs to talk to you in English around the house please Blitzo xD
He'll remind him by just staring at him blankly and saying 'The fuck are you saying?"
Also, I've decided he'll be wearing the rabbit ears
Oooh?
I figured having Blitz be extra flirty and want to be the center of attention suited him