U+309A COMBINING KATAKANA-HIRAGANA SEMI-VOICED SOUND MARK

U+309A was added to Unicode in version 1.1 (1993). It belongs to the block Hiragana in the Basic Multilingual Plane.

This character is a Nonspacing Mark and inherits its script property from the preceding character. It is also used in the scripts Hiragana, Katakana.

The glyph is not a composition. It has a Wide East Asian Width. In bidirectional context it acts as Nonspacing Mark and is not mirrored. The glyph can, under circumstances, be confused with 15 other glyphs. In text U+309A behaves as Combining Mark regarding line breaks. It has type Extend for sentence and Extend for word breaks. The Grapheme Cluster Break is Extend.

The Wikipedia has the following information about this codepoint:

Dakuten (濁点, lit. "voicing mark"), colloquially ten-ten (点々, "dots"), is a diacritic sign most often used in the Japanese kana syllabaries to indicate that the consonant of a syllable should be pronounced voiced, for instance, on sounds that have undergone rendaku (sequential voicing).

Handakuten (半濁点), colloquially maru (丸, "circle"), is a diacritic used with the kana for syllables starting with h to indicate that they should instead be pronounced with [p].