Complex sentence: In the Japanese police organization, only the Metropolitan Police Department becomes "the bureau" where security police becomes independent, and in the other prefectures Police, Public Security Section and Foreign Affairs Division are installed in a Security Department.
Split into simpler sentences: In the Japanese police organization, only the Metropolitan Police Department becomes "the bureau" where the security police branch becomes independent. In other prefectural police forces, the Public Security Section and Foreign Affairs Division are installed in a Security Department.