CREATE TABLE table_64456 ("Kanji" TEXT, "Name" TEXT, "Builder" TEXT, "Laid down" TEXT, "Launched" TEXT, "Completed" TEXT)

when was the ship completed when laid down is 21 august 1925?
SELECT "Completed" FROM table_64456 WHERE "Laid down" = '21 august 1925'
SELECT "Completed" FROM "table_64456" WHERE "Laid down" = '21 august 1925'