user: Question: Who was the winning driver at Okayama International Circuit?
Columns: ['Round', 'Circuit', 'Date', 'Pole Position', 'Fastest Lap', 'Winning Driver', 'Winning Team']
Types: ['real', 'text', 'text', 'text', 'text', 'text', 'text']
Sample row: [1.0, 'Fuji Speedway', '6 April', 'Tsugio Matsuda', 'Yuji Tachikawa', 'Tsugio Matsuda', 'Team Impul']
SQL:

assistant: SELECT "Winning Driver" FROM "Table" WHERE "Circuit" = 'Okayama International Circuit';