Only care about humans... Well, that's true but frankly speaking, he can't really blame them for it. All his instincts are telling him this kid is dangerous, but even so, he'll still try and help her!
"I mean, they won't know you're any different than a human so long as nobody starts ending up dead around the place or something! Just don't hurt anyone and they won't be of any harm to you Sayaka."
She's not gonna hurt anyone right? Sure she was uh... Animal-ish at first, but he's always wanted to think the best and give people a chance! He'd then glance between the two of them. Geez, one with no memory and the other with dead parents. These kids clearly needed someone to help out.
"Anyway, I'm not gonna try and push anything off on you two... But I can say that I highly suggest against being homeless ya know? My family almost ended up like that back when I was younger, would have if Match didn't help us out..."
The man nods at Rasa, his fists forming balls as he looks down a bit at the mention of the real Match. As for letting anyone know about Sayaka...
"Don't worry, no one would buy it if even I said it! Funny considering they know I've got a flask that leads to an endless void of water, but apparently vampires are too out there? Either way, I'll keep that bit quiet for you two!"
The man reaches into his business suit, digging out a bit of paper and two keys from it. He'd hand the paper to Rasa, along with offering each of the two a key.
"Here's the address, and keys of course! Anyway uh, the place should have a fridge, a bed, all that stuff... But I doubt there's any food, oh and the phone number on that paper is mine by the way. For some unknown reason, the place has a... Landline? I think it's called that, I don't use anything but cellphones so I'm not sure why! But if ya need to get in touch please do! Anyways, it's been nice meeting you both but I've gotta head out! Paperwork to be done so nobody questions you two moving in, filling out a report on that meeting with the Faker, and of course a firefighter's work is never done!"
With that Mizui dashes off into the night, after a while one might hear the roar of a motorcycle engine turning on. The man himself grinning below a helmet as he cruises through city streets and off to "his lair", AKA Tokyo Fire Department.