user: Question: how many revised hepburn when english is Roman characters
Columns: ['English', 'Japanese', 'Kana spelling', 'Revised Hepburn', 'Kunrei-shiki', 'Nihon-shiki']
Types: ['text', 'text', 'text', 'text', 'text', 'text']
Sample row: ['Roman characters', 'ローマ字', 'ローマじ', 'rōmaji', 'rômazi', 'rômazi']
SQL:

assistant: SELECT COUNT("Revised Hepburn") FROM "Table" WHERE "English" = 'Roman characters';