The Tà Âseiha or was a loose political coalition in the Imperial Japanese Army active in the 1920s and 1930s. The term Tà Âseiha was not a self-designated name; it was a pejorative label coined by their rivals in the revolutionary Kà Âdà Âha (Imperial Way Faction) to describe the generally conservative officers who opposed their spiritual radicalism and aggressive anti-modernization ideals. Often associated with leaders such as Lieutenant General Tetsuzan Nagata (until his assassination in 1935) and Hideki Tojo, the coalition was primarily alleged to favor maintaining Japanese imperialism under the rule of law and prioritizing military modernization with the existing state bureaucracy to prepare for total war. During the February 26 Incident in 1936, the Kà Âdà Âha assassinated alleged members of the Toseiha faction in hopes of starting a revolution, but this failed; the Kà Âdà Âha was dissolved and its leadership was purged.
The Empire of Japan had enjoyed economic growth during The First World War but this ended in the early 1920s with the Shà Âwa financial crisis. Social unrest increased with the growing polarization of society and inequalities, with the labor unions increasingly influenced by socialism, communism and anarchism, but the industrial and financial leaders of Japan continued to get wealthier through their inside connections with politicians and bureaucrats. The military was considered "clean" in terms of political corruption, and elements within the army were determined to take direct action to eliminate the perceived threats to Japan created by the weaknesses of liberal democracy and political corruption.
An ultranationalist faction within the army called the Kà Âdà Âha (Imperial Way) was formed by General Sadao Araki and his protégé, Jinzaburà  Masaki, who envisioned a return to an idealized pre-industrialized, pre-westernized Japan. The Tà Âseiha formed in reaction to the radical Kà Âdà Âha and attempted to represent the more conservative and moderate elements within the army. The Tà Âseiha and Kà Âdà Âha both adopted ideas from totalitarian and fascist political philosophies, and shared the fundamental ideals that national defense must be strengthened through a reform of national politics and espoused a strong skepticism for political party politics and representative democracy. Although the factions shared key ideals, opposition was based on how to achieve them.
The name Tà Âseiha was a pejorative exonym coined exclusively by Kà Âdà Âha members and their sympathizers. Officers assigned to this "faction" never characterized themselves as such, and it lacked any formal organization or self-identified membership. It was an institutional alignment of staff officers within the Ministry of War and the General Staff who adhered to bureaucratic procedures and modern military planning. As the Chief of the Military Affairs Bureau, Tetsuzan Nagata was viewed by radicals as the mastermind of a conspiracy whose institutional power stifled the Kà Âdà Âha. His role in the forced retirement of the Kà Âdà Âha leader General Jinzaburà  Masaki led to Masaki himself encouraging the view that his dismissal was a conspiracy engineered by Nagata, a claim the rebels accepted as fact. This culminated in the Aizawa Incident in August 1935, when Lieutenant Colonel Saburà  Aizawa assassinated Nagata in his office, claiming he was slaying a traitor who was corrupting the army. Aizawa's trial was transformed into a platform for supporters of the Kà Âdà Âha to justify his actions and further spread the myth of a Toseiha conspiracy.
The Tà Âseiha was a non-regional coalition, as opposed to Araki's reintroduction of regional politics into army promotions and policy decisions. Many Tà Âseiha members were promising graduates of the Imperial Japanese Army Academy and Army Staff College, and were concerned about Araki's emphasis of the spiritual morale of the army instead of modernization and mechanization. Rather than the confrontational approach of the Kà Âdà Âha, which wanted to bring about the Showa Restoration through violence and revolution, the Tà Âseiha sought reform by working within the existing system. The Tà Âseiha foresaw that a future war would be a total war, and to maximize Japan's industrial and military capacity would require the cooperation of Japan's bureaucracy and the zaibatsu conglomerates which the Kà Âdà Âha despised.
The Kà Âdà Âha strongly supported the hokushin-ron ("Northern Expansion Doctrine") strategy of a pre-emptive strike against the Soviet Union in the belief that Siberia was in Japan's sphere of interest. Although there were supporters of the Northern Expansion in the Tà Âseiha, the faction largely favored a more cautious defense expansion.
In late 1931, the Manchurian Incident and the subsequent Japanese invasion of Manchuria saw the two factions struggle against each other for greater influence over the military. The Kà Âdà Âha were initially dominant, but after Araki's resignation in 1934 due to ill health their influence began to wane. The February 26 Incident in February 1936 caused a widespread purge of the Kà Âdà Âha leadership from the military and the faction was de facto dissolved, while the Tà Âseiha became the dominant influence in the Japanese military but lost most of its ' and gradually disbanded.