Definitions:

The Peace Preservation Law (Chian-ijihô) was passed in Japan in 1925 as a mechanism for the Imperial family to entrench itself against a growing left wing. It forbade conspiracy or revolt against the kokutai, or national essence, of Japan, and effectively criminalized socialism, communism, and other ideologies that would threaten Japan's emperor-centered social order.

http://www.free-definition.com/Peace-Preservation-Law.html

According to the Kodansha Encyclopedia of Japan, the Peace Peservation Law was the "central pillar of the system if ideological control established in the prewar period and served as the fraework for the creation of special techniques for handling 'thought criminals' (shisouhan)." Special Higher Police (the Tokko) were created to regulate the content of motion pictures, political meetings, and election campaigns.

The main thrust of the law was presented in article 1, which read: “Anyone who has formed an association with the objective of altering the kokutai or the system of private property, and anyone who has joined such an association with full knowledge of its object, shall be liable to imprisonment with or without hard labor for a term not exceeding ten years.” By the use of the highly enigmatic and emotional term kokutai—the political system, regarded as unique to Japan, embodied in the imperial line and the institutions supporting it—the Hiranuma clique blended politics and ethics in a traditional manner, turning dissent into a moral as well as a legal issue and undermining the liberal interpretation of the Constitution of the Empire of Japan.

On the Special Higher Police

Before the World War II, the government of Imperial Japan had an
organization of secret police, called Tokubetsu Koto Keisatsu, or "Tokko"
in short. The name itself means "special high police." It was established
on August 21, 1911.

The Tokko's purpose was to suppress "dangerous thoughts," such as anti-
emperor ideologies, anti-goverment movements, and in a sense was similar to the gestapo in NAZI Germany. Their primary targets were communists, socialists, anarchists, leftists, labor
unions, various religious groups other than shinto, and Koreans living in
Japan. Numerous innocent citizens were accused of transgressions against the
emperor or of violating the Public Peace Act. The Tokko tortured and
interrogated suspects so severely that many lives were lost. Reporting suspected violators
was also encouraged.

Their official purpose was to regulate right wing movements; however, the Tokko itself inclined toward the politcal right. So many nationalists and yakuza were often left alone from Tokko suppression. In addition, some of these types of people were hired by the Tokko to harrass labor unions and Koreans.

The Tokko was independent of the normal police, and Tokko detectives could
give orders to normal police detectives. So, quite often, Tokko and normal police were
at odds with each other. The Tokko was secretive, and was greatly feared by normal police
detectives. Zaibatsu (megacorps) hated the Tokko, too. The Tokko did not regard
economic affairs very highly, so they would often break away from corporation's control. Even high
commanders of the army, who were the most powerful men in Japan in those days, could not
ignore the Tokko. The Tokko was dessolved on October 4, 1945, by the direct order of
Douglas MacArthur, the commander of the occupation forces.

BTW, the Tokko are not to be confused with the Kempaitai, the feared military police. Perhaps the Kempeitai are more like the Gestapo than the Tokko. Below is a brief account of how the Kempeitai operated in occupied Singapore during the war:

Order was strictly maintained by the Kempeitai (the Japanese Military Police). The Kempeitai were brutal and cold-blooded. People lived in constant fear of them. In many cases, ordinary people were tortured or executed on mere suspicion, or for disrespect to Japanese soldiers.

Yet, hunger and poverty forced some to steal food from shops. Those caught were dealt with harshly -- the Kempeitai cut their heads off and displayed them in public.

As the days dragged on, many were not sure if they would survive the Occupation as the Japanese became more harsh, cruel and erratic in the way they ran the country.

Some General comments on the age--the 1920s from: http://mdn.mainichi.co.jp/japano/meiji-millennium/Meiji07.html

Mannequins first hit the nation's shores in 1928, sparking a massive boom for store dummies. Mannequin clubs popped up everywhere and people would pose for photos alongside the dolls in the same way many Japanese - at least until just a few years ago - swooned at the idea of being in snapshots with Western foreigners, even if they'd only just met.

It was perhaps appropriate that the dummies assumed such a prominent role during the period from 1925 to 1929 as it appears authorities viewed them as a role model for the people.

The Peace Preservation Law of 1925 promised a prison sentence of up to 10 years for anyone who threatened the kokutai - an enigmatic term based on the belief in the unique nature of Japanese history and the fundamental role of the Imperial Family. Around the same time, the Justice Ministry created a "Thought Section" to weed out subversives and courts started to try "thought crimes."

Satisfying authorities' desires to create a docile and pliant population, little public outcry surrounded the enactment of the law, nor the first time it was used in early 1926 when applied to a students' association that had pledged to study Marxism. Perhaps the law's effects were softened when, a month after it was enacted, the right to vote was extended to male household heads over 25 years of age. If nothing else, however, the Peace Preservation Law allowed authorities to quell much of the social unrest and labor agitation that had been the hallmark of the century to date--a notable achievement in a nation where conditions for such outbursts of public anger were undoubtedly rife.

Although much of the rest of the industrialized world enjoyed heady times in the late '20s, the nation's business fortunes waned. Despite labor laws that gave companies optimum opportunities to make hefty profits, failure in business was far more common than success. Bank runs became almost an everyday occurrence in early 1927. By April of that year, the government effectively had to bring commerce to a halt--banks and stock exchanges were shut down for a month, the nation's downturn heralding the fate that was to befall the rest of the world 18 months later when Wall Street collapsed and the Great Depression began.

Much of the blame for the nation's gloomy business state can probably be laid on the military, which continued to devour almost half the annual national budget, despite the late '20s being a time of global disarmament to which Japan paid at least lip service.

The time from 1925 to 1929 is also remarkable because it signaled the official start of Emperor Hirohito's reign, possibly the most tumultuous in the nation's history.

The period was also a time to start national traditions with dubious benefits. Ferroconcrete apartments appeared for the first time, in Tokyo's Harajuku district. Within generations, the nation's cities had been almost concreted over. Moreover, on July 24, 1927, Ryunosuke Akutagawa, probably the greatest author of his generation, killed himself. The suicide of Akutagawa, who gives his name to the nation's most prestigious literary award, was later mimicked by other great Japanese writers such as Osamu Dazai in 1948, Nobel laureate Yasunari Kawabata in 1971 and, perhaps most notably, in 1970 when Yukio Mishima slit his belly while trying to urge Self-Defense Force troops to revolt.

The Modern Girls (1920s)
Harbingers of today's teens

Before Louis Vuitton bag-toting gals in the '80s and loose-socked, prostituting pheromones of the '90s, the '20s had the modern girls.

The moga, as the women were known, modeled themselves on the flappers of the West. Their prestigious occupations (for the time) as elevator girls, receptionists or telephone exchange operators made them the darlings of women who aspired to a life filled with more than merely childbirth and hard labor coupled with undying devotion to their man.

Despite the nation's embryonic suffragette movement, moga were generally apolitical. Moga were probably the first group of Japanese women to enjoy widespread freedom.