Sony said it would offer the world’s first notebook PC equipped with a next-generation Blu-ray optical disk drive in Japan in June, a month behind Toshiba’s launch last week of laptop PCs with a rival drive. Sony also said it would unveil in June a handheld PC that uses NAND flash memory instead of a hard disk drive as its storage, in a potential boost to NAND flash makers such as Samsung Electronics and Toshiba.