Try Toyoshokuhin in Chatham Square in Cary. Sadly, she doesn't really carry any bento accessories or boxes. But, it *is* a Japanese store and she makes incredible inarizushi and mochi. And she just gives it away with purchases!
I've seen the laptop lunch kits and supplies at Twig, a store right near Whole Foods in Chapel Hill, and Kitchenworks in University Mall on Estes Dr in Chapel Hill has a very good selection of cookie cutters. But so far I have not been able to find any good Japanese bento supplies in the area!