Origins

In November 1945, a diverse grouping of non-Communist proletarian and peasant-based groups established the Japan Socialist Party. Its official English name was the Social Democratic Party of Japan. The story behind this nomenclature sheds some light on the party’s internal fault lines.

In the preparatory meeting leading up to the party’s establishment, members of its right-wing faction had argued that it should be called the “Social Democratic Party.” Left faction members pushed for “Japan Socialist Party” instead and won by just one vote. Their factional opponents had their name adopted in English as consolation prize, although it was seldom used throughout the party’s fifty-year history.

The non-Marxist right faction rejected the idea of cooperation with communists and sought to reform the capitalist economy rather than overthrow it. The Marxist left faction derived from a group that aimed for a revolution in Japan that would be independent from Moscow’s orders. While it remained wary of Soviet influences, it did not rule out cooperation with Japanese communists in its pursuit of socialist revolution.

In contrast to the Japanese Communist Party (JCP), whose leaders emerged triumphantly from prison in October 1945 as the only ones to have resisted the wartime monarchist regime, JSP leaders from its right faction had been active collaborators of that regime. When the Class-A war criminal Kishi Nobusuke reentered politics after three years in prison, he considered forming a political party that would absorb a portion of the JSP.

Kishi even sought to join the group established by the JSP’s right faction after the party split in 1951. These moves were not surprising: while some of Kishi’s political protégés set up a party that would eventually merge into the conservative LDP, others had joined the newly established JSP.

The right faction’s close ties with the wartime regime weakened them in their struggles with the JSP left, but the power balance nonetheless favored them during the early years of the party. While the party was by no means immune from factional infighting at that time, the overriding goal of economic reconstruction in Japan kept the more divisive ideological battles at bay.

Early Success

In the 1947 general election, the JSP became the largest party in the House of Representatives. With 143 seats and 26.2 percent of the vote, it edged out the conservative Liberal Party (131 seats) and Democratic Party (124 seats), although its vote share was slightly lower than that of the Liberals. General Douglas MacArthur saluted the election result as a sign that the Japanese people under his rule had chosen the “middle of the road course” in politics.

JSP leader Katayama Tetsu celebrated his party’s victory as the arrival of a new era in which the “progressive forces” led by the JSP would play a leading role. However, the most powerful figure in the JSP leadership did not share the celebratory mood. Hearing news of his party’s surprising victory on the night of the election, Secretary General Nishio Suehiro famously blurted out, “Oh, crap.”

With the conservative parties who had finished second and third together holding an overwhelming majority, Nishio sought to avoid a scenario where an underprepared JSP would be thrust into a position of leadership. He attempted to convince the conservative incumbent Yoshida Shigeru to remain as prime minister. Yoshida refused, and the first cabinet to be formed under Japan’s postwar constitution became a Socialist-led government with Katayama at its head.

The Katayama government fell eight months after its formation when an overwhelming majority in the Diet rejected its proposed budget. It was not the opposition parties or the conservative coalition members that led this move against Katayama but rather JSP leaders from the left faction, who blocked Katayama’s scheme for a public sector wage hike in order to sabotage a cabinet it abhorred.

The JSP joined the next administration, led by the conservative prime minister Ashida Hitoshi, which only lasted seven months in office. It collapsed after G-2, the intelligence arm of the US occupation forces, leaked secret information about an extensive corruption scandal implicating Ashida and key leaders connected to his coalition government, including the JSP leader Nishio. The increasingly powerful G-2 staged the revelation of systemic corruption so as to bring down the moderately left-wing Ashida government, which was backed by reformist elements within the occupation administration.

A trial that dragged on in the courts for thirteen years ultimately found Ashida, Nishio, and other politicians to be innocent of the charges against them. However, their highly publicized arrests in 1948 heavily tarnished the JSP’s image. The party lost two-thirds of its seats in the 1949 general election, with its vote share declining to 13.5 percent. It would not join another ruling coalition for over four decades.

The 1951 Split

The organizational basis for the Left JSP’s rise in the early 1950s was Sōhyō. This union federation had been established in July 1950 with the backing of the US occupation regime (GHQ), on the ruins of the JCP-led Sanbetsu (All Japan Congress of Industrial Unions) movement. The US-backed Red Purge of the late 1940s and early 1950s had broken Sanbetsu, with tens of thousands of alleged communist sympathizers sacked from their jobs in the public and private sectors.

GHQ and others hoped that Sōhyō would develop into a moderate and apolitical union that would bargain for improved wages and not much more. However, things worked out very differently in practice. While corporate management could purge Sanbetsu activists and appoint cooperative company men in union leadership positions, they could not win over the rank-and-file workers who had firsthand experience of the postwar disruption of old workplace relations.

For these workers, the offensive launched by the Japanese authorities after the Red Purge with US support was an integrated crisis. The revival of prewar workplace culture and the rehabilitation of former war criminals combined with the spectacle of Japanese rearmament during the Korean War to strengthen the perception that Japan was hurtling back toward its very recent past.

In the face of this crisis, the compromising attitude of the Right JSP leaders toward the San Francisco Peace Treaty seemed reminiscent of the opportunistic support for imperial expansion by prewar socialist politicians. Worker activists quickly transformed Sōhyō into a powerful political force that lay behind the Left JSP’s split with its right-faction partners and its subsequent rise.

They established a distinctive political culture within the framework of Japan’s postwar democracy. Labor unions played a leading role in political mobilization around issues relating to peace, including anti-base activism, the antinuclear movement, and the protests against the US-Japan Security Treaty (known as Anpo) in the late 1950s. Sōhyō’s activism struck a popular chord during the 1950s and succeeded in mobilizing a “Never Again” sentiment against reactionary tendencies.

Parting Company

Confronted with such an enemy, the calls of the JSP’s right faction for compromise and dialogue had limited appeal. For supporters of the left faction, shamin — the shorthand term for social democrats — was a dismissive label with connotations of spinelessness. The main source of the JSP’s radicalization during the 1950s was opposition to the reverse course. Its radicalization over the ensuing decade stemmed from an internal struggle against the shamin tendency.

As the Anpo controversy intensified, the leader of the JSP right, Nishio Suehiro, continued to stress the need for moderation. He accused the party leadership of irresponsibility for opposing the Anpo treaty without offering realistic alternatives. Nishio left the JSP and established the Democratic Socialist Party (DSP) in January 1960. In both foreign and domestic policy, the DSP sought to position itself between the LDP and the JSP, calling for the “gradual” abolition of the Anpo treaty and incorporating principles adapted from the West German Social Democratic Party’s Bad Godesberg program of 1959.

Aiming to establish itself as the largest opposition party, the DSP ran 104 candidates in the November 1960 general election. However, only 17 were elected, while the JSP won 145 seats. The JSP’s vote share was three times higher than that of the DSP. Together, the parties had more than 36 percent of the vote — a stronger performance than the presplit JSP had managed in 1958.

The biggest reason for the DSP’s setback was its moderate position on the Anpo issue. This proved to be deeply unpopular with left-wing Japanese voters, especially after the Kishi administration rammed through the treaty bill in May 1960, a polarizing move that triggered massive street protests before the treaty’s automatic approval one month later.

For the rest of the 1960s, ’70s, and ’80s, the DSP retained a foothold in national politics, always receiving somewhere between 6 and 8 percent of the vote. But it never threatened to supplant the JSP as the main force of the Japanese left.

After the treaty finally passed, there was a marked shift in the political mood. Kishi resigned as prime minister to be succeeded by Ikeda Hayato, who turned away from the confrontational approach of his predecessor. With considerable success, Ikeda redirected the nation’s energies away from political contention and toward the pursuit of economic growth. He announced with great fanfare that Japan was going to double its income in ten years.

Although he was initially seen as a coldhearted bureaucrat with a reputation for politically insensitive remarks, Ikeda remade his public image. He changed his glasses and suit, proclaimed his love of the plebeian Japanese curry rice, and refrained from taking part in golf outings and geisha parties in order to come across as a relatable, clean, and benign leader.

A corresponding shift seemed to be occurring in the JSP after a right-wing youth assassinated the party chairman Asanuma Inejirō in October 1960. His successor, Eda Saburō, was a proponent of “structural reform.” This was a tendency that arose as an attempt to overcome the party’s dependence on labor unions by harnessing the popular energy of a wider group of activists that emerged as a political force during the 1960 protests. Like Ikeda, Eda was a media-savvy politician, and it appeared that he might be able to lead the JSP into a new era.

Eda and the Boom

While Ikeda was able to cool down the LDP’s factional antagonisms with his call for economic growth, Eda’s political strategy triggered a backlash inside the JSP. He alienated union activists from the JSP left by essentially characterizing the yearlong struggle by miners at the Mitsui Miike Coal Mine in southern Japan as an insignificant act of resistance by workers in a doomed industry. His smooth-talking TV appearances also raised hackles among supporters of the left faction.

Eda then further enraged JSP activists by proclaiming that his vision of a “broad-based socialism” would seek to incorporate “America’s high standard of living, the Soviet Union’s thoroughgoing social welfare system, England’s parliamentary democracy, and Japan’s peace constitution.” For his inner-party opponents, this vision of socialism was too broad to be considered socialist at all.

The DSP leader Nishio Suehiro, a hate figure for the JSP left, declared that he “fully supported” the structural reformists. This remark was guaranteed to taint Eda in the eyes of the left faction: in effect, Nishio sabotaged a JSP movement that was threatening to encroach upon the DSP’s social democratic turf. The JSP promptly adopted a resolution renouncing Eda’s vision and forced him to resign as secretary general at its party conference held in November 1962.

Although the DSP preserved its monopoly over the social democratic position in Japanese politics, it was unable to expand its political base during the 1960s. With the allure of rising incomes and expanding benefits for employees of private firms crowding out arguments for redistribution and social security, the party’s call for a welfare state only received a lukewarm response from the Japanese public.

The rise of what can be termed the “welfare company” in a time of rapid economic growth undermined support for the DSP and JSP alike. During the time of the reverse course, a frontal assault on labor activism had radicalized workers. Sōhyō’s affiliated unions, based in big companies and the public sector, formed the organizational basis for the left faction of the JSP.

However, in the subsequent period of economic growth, the major Japanese firms adopted a more sophisticated approach in the workplace to tame the unions. They put wage structures in place that promoted competition between workers while offering their employees benefits such as long-term loans for home ownership and pensions that bound them to the firm in a new relationship of dependent co-prosperity.

Within this new company-centered framework, white-collar and blue-collar workers both tended to perceive the improvement of one’s position and pay levels through the pursuit of individual success to be a more attractive course than union activism that would deliver collective gains. They also increasingly accepted the notion that corporate success best served their own interests and believed that the political party most likely to advance those interests was the LDP.

Stagnation

The proponents of “structural reform” in the JSP sought to move away from a union-based politics whose days were numbered. Their opponents fought off this attempt by empowering New Left youth groups and the Socialist Association headed by the Leninist theorist Sakisaka Itsurō. After defeating the structural reformists, these militant groups were unwilling to be demobilized. Their efforts led to the party’s adoption in 1966 of a doctrinaire platform premised on the imminent collapse of Japanese capitalism.

By this point, the Japanese Communists had begun distancing themselves from the Soviet Union and their own insurrectionary past, adopting a more flexible and moderate stance that was in tune with domestic political realities. A radicalized JSP moved in to fill the vacuum. When Soviet forces invaded Czechoslovakia in 1968, the JCP unequivocally denounced it as an act of aggression, while the JSP’s reaction was mixed, with some influential members openly voicing support for the invasion.

In general elections held the following year, the JCP increased its number of seats in the lower house from five to fourteen, inaugurating a period of growing Communist popularity under the leadership of Miyamoto Kenji. Meanwhile, the JSP suffered a major setback from which it never fully recovered, dropping from 140 to ninety MPs. In the first three elections of the decade, its average vote share had been 28 percent; now, it dropped to 21.4 percent.

Over the course of the 1970s and ’80s, the JSP retained its position as Japan’s second-largest party, but the prospect of the Socialists overtaking the ruling LDP seemed ever more remote. In every election from 1969 to 1986, the LDP won at least twice as many votes as the JSP. In 1979, the Socialist vote dropped below 20 percent for the first time since the left and right factions had reunified in the 1950s. It remained below that threshold during the 1980s.

In 1986, the JSP formally abandoned the platform it had adopted two decades earlier and adopted a new stance affirming the principles of social democracy. The same year, the party’s performance in the lower-house election was its worst to date, with 17.2 percent of the vote. Support for the LDP was almost three times greater. That setback forced the JSP’s existing leadership to resign.

Revival and Collapse

Doi Takako, a political novice whose leadership was seen as a stopgap measure by party insiders, became the new leader. She was a new, straight-talking face who did not come from a trade union background. In 1988, she rejected the LDP’s unpopular proposal to introduce a tax on consumption with a phrase for which she became famous: “What is unacceptable is unacceptable.”

Greatly aided by a series of scandals that engulfed the LDP, the JSP overtook the ruling party in the upper-house election of 1989 under Doi’s leadership, with 35.1 percent to the LDP’s 27.3 percent — a swing of almost 30 percent between the parties since the previous election in 1986. The following year, the JSP took over 24 percent in the lower-house election, its best performance since the mid-1960s.

However, the JSP could not build on this success. By the time of the following election, public anger against the LDP had weakened, while the JSP’s opposition to legislation that would allow Japanese participation in United Nations peacekeeping missions proved to be unpopular with the Japanese public. In the upper-house election of 1992, the JSP’s vote share halved, and the party lost nearly half its seats in the lower house in 1993.

In 1994, the JSP decided to form a coalition with the LDP. Although the ruling party had suffered a major setback in the 1993 election, with the worst performance in its history to date, it still had three times as many MPs as the JSP. However, JSP leader Murayama Tomiichi became Japan’s prime minister — the first Socialist politician to hold that position since the late 1940s, and the last.

Murayama abruptly announced a “great transformation of policy” in the JSP, expressing support for Japan’s military alliance with the United States and deeming the Self-Defense Forces to be constitutional. Since the JSP had built its identity around an oppositional stance on these issues, supporters of the party perceived its “great transformation” as a great sellout.

In January 1996, the JSP renamed itself the Social Democratic Party (SDP), adopting the name that had been rejected by a narrow margin at the time of its foundation. The new organization inherited the JSP’s position as the second-largest force in the Japanese party system, which it had maintained for almost four decades (or five, if one combines the support for Left and Right JSPs in the 1950s). It had lost that position by the end of the year: in the lower-house election of October 1996, the SDP came in fifth with 6.4 percent of the vote and just fifteen seats.

After the JSP

The Social Democrats have spent the years since then battling for survival, barely surpassing the minimum 2 percent vote share needed to participate in national politics. The JCP, which did not change its name, has been far more successful than the SDP in the post–Cold War era, achieving some of its best-ever electoral performances.

After its coalition with the LDP and the short-lived New Party ended in 1998, the SDP returned to the opposition benches, apart from one very brief stint in government as part of an alliance headed by the Democratic Party of Japan (DPJ). The DPJ itself had absorbed a large group of former JSP politicians when it was established in 1996: roughly 45 percent of its original members in the House of Representatives had JSP roots. However, this percentage fell rapidly in the ensuing elections, dropping to below 5 percent after the 2009 election.

With influential leaders coming from a conservative LDP background, the DPJ occupied an electoral space well to the right of the JSP and SDP. In 2020, the DPJ’s successor party, the Constitutional Democratic Party of Japan (CDP), approached the SDP with a merger proposal. Three of the four SDP House of Representatives members joined the larger party, leaving behind party leader Fukushima Mizuho as the sole remaining SDP politician in the chamber.

Yet Fukushima remains defiant:

People think that the Social Democratic Party is a party of the past. But the issues for which we have long advocated, like human rights and gender equality, are issues for the future. Young people are showing interest. The young generation and women are key groups for us. We want to connect with them, renew the party, and energetically work toward a revitalized Social Democratic Party.

Is there any basis for Fukushima’s optimism? As a tiny party with little to lose, the SDP may be able to respond to new social democratic needs and opportunities in ways that are not open to more mainstream parties like the CDP. Clearly, Japanese society will not be lacking in such needs and opportunities for the foreseeable future.