This symbol is called 米印 kome-jirushi ("rice sign") in Japanese, because of its resemblance to the kanji for rice.

It is superficially similar to an English asterisk, but actually used quite differently. Most of the time, the kome-jirushi appears to draw the reader's attention to instructions or precautions, e.g.:

Dismembering the monkey is prohibited by law.
Like the asterisk, the kome-jirushi can also be used for footnotes. Nowadays, however, it is more common to use numbered footnotes or a Western-style asterisk ( / Unicode FF0A) for that purpose.

The kome-jirushi appears at Unicode hex 203B.