user: Question: Which Opponent has the Event of Sengoku 1?
Columns: ['Res.', 'Record', 'Opponent', 'Method', 'Event', 'Round', 'Time', 'Location']
Types: ['text', 'text', 'text', 'text', 'text', 'real', 'text', 'text']
Sample row: ['Win', '6-5', 'Jae Sun Lee', 'Decision (unanimous)', 'Sengoku 10', 3.0, '5:00', 'Saitama , Japan']
SQL:

assistant: SELECT "Opponent" FROM "Table" WHERE "Event" = 'Sengoku 1';