It should be
mentioned that there are several
obsolete kana that are rarely used today, in both hiragana and katakana. In hiragana:
ゑ - the "we" hiragana
ゐ - the "wi" hiragana
ゔ - the "vu" hiragana
All of these kana are
considered obsolete, and exist only for use in
transcribing older documents. In cases where the "vu" hiragana is used, the still in use katakana "vu" is placed instead, and when formed into another
syllable, a smaller
kana vowel is paired with it.
There are an
additional 4 obsolete characters in
katakana, none of which have a hiragana form.