Wellllll...I'm pretty convinced that Shou would recognize Natsumi since he was brought up in Japan and his family is, shall we say, somewhat celebrity-ish in nature. I doubt he'd acknowledge that he knew who she was, though, unless it was of benefit to him.
If you're looking for some kind of background storyline, it could always be possible for the two to have rubbed elbows in Japan, what with the nature of Shou's family "business." ;)