[2][3] Before World War II, the Tokyo Metropolitan Police Department (TMPD) established the Emergency Service Unit (特別警備隊, Tokubetsu-keibi-tai).

During the war, as air raids on Japan intensified and civilian casualties increased, the TMPD ESU was enhanced for relief missions and renamed as the Security Unit (警備隊, Keibi-tai).

However, in 1946, the Security Units were disbanded as part of police reforms enacted by the Supreme Commander for the Allied Powers under the occupation.

[4] Shortly after the TMPD ESU was disbanded, the Guard Section (防護課, Bougo-ka) was created for the same role.

[4] In addition, similar but smaller-scale riot squads were created in several other prefectures to deal with post-war turmoil.