the red circle is indeed called mon but there are other versions of the Rising Sun flag such as the naval flag with radiating beams, the Emperor's Chrysanthemum flag and other emblems such as the floral emblems eg the cherry blossom and iris. That's why I gave such an equivocal answer
The sun-disc is actually called maru, I believe (mon is a general term for a 'heraldic' emblem.) The sloppy question is probably looking for chrysanthemum I would guess...