13 characters in the Kana Extended-B Unicode block.
U+1AFF0KATAKANA LETTER MINNAN TONE-2U+1AFF1KATAKANA LETTER MINNAN TONE-3U+1AFF2KATAKANA LETTER MINNAN TONE-4U+1AFF3KATAKANA LETTER MINNAN TONE-5U+1AFF5KATAKANA LETTER MINNAN TONE-7U+1AFF6KATAKANA LETTER MINNAN TONE-8U+1AFF7KATAKANA LETTER MINNAN NASALIZED TONE-1U+1AFF8KATAKANA LETTER MINNAN NASALIZED TONE-2U+1AFF9KATAKANA LETTER MINNAN NASALIZED TONE-3U+1AFFAKATAKANA LETTER MINNAN NASALIZED TONE-4U+1AFFBKATAKANA LETTER MINNAN NASALIZED TONE-5U+1AFFDKATAKANA LETTER MINNAN NASALIZED TONE-7U+1AFFEKATAKANA LETTER MINNAN NASALIZED TONE-8