This is Chelnov: The Atomic Runner for the Sharp X68000, a Japanese game disk set.
The set includes the game disk, manual, and box. The disk has been tested — the title screen was confirmed to display — and comes with its original label and sleeve. Both the manual and box are original, as shown in the photos.
Mold that had formed on the floppy disk has been removed, but there's a chance the game may not work properly on your X68000 depending on its condition.
