This little eighth note (or quaver, for you Commonwealth types out there), found at Unicode hex 266A, is a commonly-used typographical character in Japanese. When you come across it in a text, it indicates that the following phrase is sung. For instance:
Kyu-chan began to sing. "Ue o mu-u-ite..."
Originally, a character called the ioriten or "cottage mark" was used to fill this function in written works, especially bunraku and kabuki scripts. The JIS character set, however, didn't include the mark, and it wasn't a part of Unicode until Unicode 3.2 (it now resides at hex 303D, assuming you have a recent Unicode font: ). In the absence of the right character, word processor users began using the eighth note mark instead.

In Japanese, the symbol is called onpu, which simply means "note."