[ Well that's what Naoto signed up for! He wasn't quite prepared for that, though—

So Sion gets to watch the faces Naoto makes as he reacts to that and they don't disappoint, and his voice goes from quietly whispering Sion's name to whimpering it to moaning it to something a lot closer to just screaming it, while his fingers twist and his nails dig in and he drags them up Sion's back—

Which means that Sion can safely cross 'make Naoto scream my name and claw my back' off his list of things to do on vacation, then. ]