This character is a Other Letter and is mainly used in the Katakana script.
The glyph is not a composition. Its East Asian Width is wide. In bidirectional text it is written from left to right. When changing direction it is not mirrored. This katakana joins with other adjacent katakana to form a word. U+30C8 offers a line break opportunity at its position, except in some numeric contexts. The glyph can be confused with one other glyph.
The Wikipedia has the following information about this codepoint:
と, in hiragana, or ト in katakana, is one of the Japanese kana, each of which represents one mora. Both represent the sound [to], and when written with dakuten represent the sound [do]. In the Ainu language, the katakana ト can be written with a handakuten (which can be entered in a computer as either one character (ト゚) or two combined characters (ト゜) to represent the sound [tu], and is interchangeable with the katakana ツ゚.