CREATE TABLE table_54356 ("Res." TEXT, "Record" TEXT, "Opponent" TEXT, "Method" TEXT, "Round" FLOAT, "Time" TEXT)

What method was used that had a resulting win against opponent, Natsuko Kikukawa?
SELECT "Method" FROM table_54356 WHERE "Res." = 'win' AND "Opponent" = 'natsuko kikukawa'
SELECT "Method" FROM "table_54356" WHERE "Opponent" = 'natsuko kikukawa' AND "Res." = 'win'