The string "Hatsune Miku Project DIVA Mega Mix -NSP--US--26..." appears to refer to a specific digital file format (NSP) for the Nintendo Switch version of the rhythm game Hatsune Miku: Project DIVA Mega Mix , likely associated with game backups or sideloading.
Introduction
In the context of Project DIVA Mega Mix, the -US- tag indicates the North American localization. This is vital because the US version differs from the Japanese (JP) and European (EU) releases in several ways: Hatsune Miku Project DIVA Mega Mix -NSP--US--26...
One polarizing feature in the US NSP is the default “Mega Mix” visual filter. SEGA re-rendered many PVs with cel-shading to mimic the official Miku concerts. Purists hated it. Casual players loved it. The string "Hatsune Miku Project DIVA Mega Mix -NSP--US--26