user: Question: Which event led to a 4-0 record?
Columns: ['Res.', 'Record', 'Opponent', 'Method', 'Event', 'Round', 'Location']
Types: ['text', 'text', 'text', 'text', 'text', 'real', 'text']
Sample row: ['Win', '16-5', 'Wataru Inatsu', 'KO (punches)', 'ZST 9 - The Battle Field 9', 1.0, 'Tokyo , Japan']
SQL:

assistant: SELECT "Event" FROM "Table" WHERE "Record" = '4-0';