Who will be the next Prime Minister of Japan?(2025)

The 2025 LDP Presidential Election: Predicting the Next Prime Minister at the Intersection of Elder Rule and Populism

Introduction: The Structural Specificity of the 2025 LDP Presidential Election

The 2025 Liberal Democratic Party (LDP) Presidential Election, prompted by the expiration of Prime Minister Fumio Kishida’s term, possesses structural idiosyncrasies rarely seen in recent LDP leadership contests. The dramatic dissolution of factions, particularly the Seiwa-kai (Abe faction), following public scrutiny over political funding issues, has paradoxically led to an external appearance of transparency while simultaneously facilitating the concentration of power among key political Elders. This election is thus constrained by two principal forces: the pragmatic demand to select an "electable face" for the upcoming general election, and the strategic imperative of the Elder class to implement a "risk minimization" strategy.

The core analysis confirms that a runoff election is structurally inevitable.Given the expected large number of candidates and the lack of a dominant, unifying faction, no single candidate is likely to secure an outright majority in the first round. Consequently, the runoff mechanism, where the weight of Diet member votes becomes overwhelming, will decisively determine the next LDP President. This report analyzes the logic under which the Elders—prioritizing stability, avoiding ideological conflict, and ensuring a victory in the next general election—will consolidate votes around Koizumi Shinjiro as the optimal, non-threatening choice, projecting his probability of victory at 70%.

I. Transformation of Japan’s Political Climate: Elder Rule, Factional Fluidity, and the Mist of Populism

1. Historical Shifts in Factional Politics and the Post-Seiwa-kai Power Vacuum

While LDP politics have historically been driven by formalized factions, the disbandment of these groups has curtailed their formal functions as vehicles for political fundraising and personnel negotiations. The power structure has, however, evolved into a more fluid and informal system. Previously, faction leaders were constrained by the need for internal coordination; the dissolution removed these formal constraints.

The current situation is not one of decentralized power, but rather the facilitation of an "Elder-Non-Factional Coalition." Individual Diet members, deprived of the support structure of formal factions, have become directly reliant on influential Elders—specifically Taro Aso, Yoshihide Suga, and Fumio Kishida—for influence, nominations, and the aggregation of votes.This shift allows the Elders to bypass factional bureaucracy, enabling highly fluid and efficient vote mobilization, which is particularly decisive during the critical second round of voting.

2. Reconfiguration of Elder Rule: Tendencies and Intentions of the Three Elders (Aso, Suga, Kishida)

Taro Aso, Yoshihide Suga, and incumbent President Fumio Kishida are widely acknowledged as the three central figures commanding the bulk of Diet member votes.Their strategic calculus is driven by practical goals: maintaining their own influence post-term, ensuring LDP unity, and, most critically, winning the next general election.

Mr. Aso consistently seeks political stability. He aims to avoid highly ideological candidates (such as Ms. Takaichi) or candidates who might trigger internal party disputes due to strong factional ties. He is inclined to accept pragmatic individuals. Mr. Suga, conversely, places a premium on administrative reform and electoral viability. A reformist candidate with high public recognition and a detachment from the LDP’s old factional guard, like Mr. Koizumi, is a highly attractive prospect for him. Mr. Kishida wishes to maintain influence over his macro-policy legacy and protect his former bloc (Kishida faction members) but is highly motivated to avoid a divisive leadership contest that could damage party unity.

Since the collective priority of the three Elders is to prevent LDP fragmentation and ensure victory in the next general election, the success of a heavily faction-aligned candidate (Hayashi or Motegi) threatens the balance of power and the interests of the other Elders. Koizumi Shinjiro, being non-factional and centrist, emerges as the "most acceptable compromise" for all three, minimizing political risk while maximizing electoral potential. The precedent set by the 2024 election, where the Diet votes coalesced against frontrunner Takaichi in the runoff to secure victory for Ishiba, illustrates the functional readiness of this Elder coalition.

3. The Turning Tide of Populism: Shift in Voter Consciousness Indicated by Sanseito’s Rise

The trend of populism in Japanese politics is an increasingly vital factor. Following the July House of Councillors election, in which the LDP lost seats while conservative newcomers like Sanseito gained ground, Western analysts have argued that "the age of populism has finally arrived in Japan".Sanseito's platform, including policies like "Japanese First," shares characteristics with populist movements observed in Europe and the United States.

This rising populist sentiment necessitates that the LDP select a leader who can effectively address the dissatisfaction among conservative voters and strengthen the party's appeal. The dilemma for the Elders lies in balancing charisma against control. To secure party member votes, a candidate must possess public appeal, but a rigid ideologue like Takaichi is deemed an "unpredictable risk" by the Elders. The Elders require a leader who is "popular enough to counter the populist wave, yet pragmatic and controllable." Koizumi Shinjiro’s high national profile and media proficiency serve precisely as this necessary "populist counter-measure," making him a highly valuable asset to the Elders.

II. In-Depth Candidate Profile Analysis: Factional Constraints and the Disconnect from Public Opinion

A thorough understanding of the election mechanics requires analyzing the constraints and appeal of the five major candidates relative to the Elders and the general electorate.

Table 1. Candidate Strengths and Weaknesses in the Presidential Election

1. Analysis of Faction-Based Candidates (Hayashi and Motegi): The Limits of Organizational Votes

Both Hayashi Yoshimasa and Motegi Toshimitsu possess organizational strength derived from their former major factions (Kishida and Motegi groups, respectively). They are expected to secure a respectable number of votes in the first round based on these lingering organizational ties. However, the dissolution has injected uncertainty into the reliability of these votes.

Crucially, their strong factional identities limit their potential in a runoff. The Elder coalition is inherently opposed to the resurrection of concentrated factional power. A victory by either Hayashi or Motegi would signify the restoration of power to a specific bloc, threatening the delicate balance of the other Elders. Their status as "factional faces" thus acts as an anchor, preventing them from becoming the consensus choice and ensuring that other Diet votes coalesce around a non-factional alternative, specifically Koizumi, in the runoff.

2. Analysis of the Pure Conservatives (Takaichi and Kobayashi): Hardline Stance and Avoidance by the Elders

Sanae Takaichi is capable of mobilizing enthusiastic support from party members and pure conservatives due to her clear commitment to proactive fiscal policy and hardline security positions. She is highly likely to lead in party member votes in the first round. However, her structural challenge is insurmountable. She is viewed with strong aversion by the Elder class due to her policy rigidity, past association with the political funds scandal (small coffers), and ideological clarity, which they perceive as an "unpredictable risk."

The 2024 election reversal, where Takaichi—despite leading in the first round—was defeated by Ishiba in the runoff, provides a critical precedent. It demonstrates that the runoff mechanism functions as an internal veto designed to exclude highly ideological or polarizing candidates, ensuring that the final choice prioritizes stability and control. If Takaichi advances to the runoff, the Elders are highly likely to organize a systematic concentration of Diet votes against her, ensuring her defeat, regardless of her popular base. Takayuki Kobayashi, while conservative, lacks the necessary recognition and political following and is too dependent on the Elders to build independent momentum.

3. Analysis of the Centrist/Non-Factional Candidate (Koizumi Shinjiro): Acceptability and Expandability

Shinjiro Koizumi’s greatest assets are his centrist policy stance and his non-factional status. His policy moderation makes him politically "controllable" from the perspective of all major Elders. He does not represent the interests of any specific rival faction, minimizing the risk of internal conflict among Aso, Suga, and Kishida.

Furthermore, his high national popularity and media competency are vital for reviving the LDP’s overall approval ratings, satisfying the Elders' primary requirement for an "electable face." Because Koizumi lacks a powerful internal party base, a victory means he would remain reliant on the Elders for personnel appointments and policy backing, thereby ensuring their continued influence even in the Prime Minister’s Office. Koizumi is perceived as a "low-risk investment" and is expected to receive strong support from Mr. Suga's camp, functioning as the implicit "blank check mandate" of the Elder coalition.

III. Electoral Dynamics of the 2025 LDP Election and Runoff Simulation

1. First Round Vote Analysis: D’Hondt System and the Inevitability of a Runoff

The first round of the Presidential Election involves 295 Diet member votes and 295 Party votes (calculated using the D'Hondt proportional distribution method based on party member and associate votes nationwide), totaling 590 votes.A candidate requires an absolute majority (296 votes) to win outright.

With five candidates contesting and no central factional authority to enforce unity, the votes are guaranteed to be scattered. Given that Takaichi is likely to secure the most party votes, while Motegi and Hayashi hold organizational remnants, and Koizumi appeals broadly, it is structurally impossible for any candidate to reach the 296-vote threshold. Transitioning to a runoff between the top two candidates is unavoidable.

2. Structural Analysis of the Runoff: Clarification of the Absolute Superiority of Diet Member Votes

The structure of the runoff vote is the decisive factor in the election. The runoff involves a total of 342 votes: 295 from Diet members and 47 from the prefectural representatives (one vote per prefectural chapter).

The table below highlights the dramatic shift in the proportion of Diet member votes between the two rounds.

Table 2. 2025 LDP Presidential Election Voting Structure Analysis (First Round vs. Runoff)

As Table 1 clearly demonstrates, Diet member votes account for approximately 86.3% of the total in the runoff. This overwhelming proportion means that the "will of the party members," which contributed 295 votes in the first round, is diluted to a negligible 47 local votes, effectively neutralizing their influence. This mechanism grants the Elders direct and overwhelming power to determine the outcome, functioning as an internal safeguard to ensure that the candidate selected is one who preserves party stability and the existing power structure.

3. Lessons from the Ishiba-Takaichi Reversal (2024): The Mechanism of Elder Coalition

The 2024 presidential election provides the most crucial precedent for the current analysis. In that contest, despite Sanae Takaichi winning the first round (181 votes, including the most party votes), she was ultimately defeated by Shigeru Ishiba (215 votes) in the runoff , providing a critical lesson in the runoff dynamics. This reversal demonstrated that a trailing candidate can successfully consolidate votes from eliminated camps in the runoff, achieving victory through the strategic deployment of Diet member votes.

The reversal was predicated on a shared "anti-Takaichi" consensus among the mainstream party members and Elders, who prioritized stability and organization, resulting in a systematic concentration of parliamentary votes onto Ishiba.

In 2025, if Koizumi advances to the runoff (especially against Takaichi or a factional representative like Motegi), the same structural logic is anticipated. The votes initially cast for eliminated candidates—particularly those belonging to the non-Koizumi camp—will be strategically redirected. This redirection is driven not only by Elder instruction but also by the individual Diet members’ self-interest; they need a popular leader who is free of major scandal or policy extremism to enhance their own chances in the looming general election. The combined force of Elder guidance and individual political necessity converges strongly in favor of Koizumi.

IV. Conclusion: Prediction of Shinjiro Koizumi’s Victory (70% Confidence Level)

1. Basis of Prediction: Koizumi as the Elders’ "Optimal Solution"

Based on the comprehensive analysis of structural dynamics, historical precedents, and political incentives, Shinjiro Koizumi is predicted to win the 2025 LDP Presidential Election with a 70% confidence level. This prediction is derived from three converging structural factors:

1. Structural Certainty (86.3% Control): The structural inevitability of a runoff, where Diet member votes account for 86.3% of the total, ensures that the result is dictated by the consensus of the Elder Coalition (Aso, Suga, and Kishida).

2. Strategic Consensus: Koizumi is the only candidate who meets the consensus criteria. He is supported by Suga for his reformist image and electability, tolerated by Aso for his stability, and acceptable to Kishida's bloc because he poses no threat of resurrecting a rival faction. His victory offers the safest path for the Elders to maintain their collective influence and the current balance of power.

3. Electoral Advantage: Koizumi’s high national popularity and media presence are indispensable assets for countering the wave of populism and retaining the LDP’s overall appeal leading into the next general election. His success is viewed favorably by Diet members concerned about their own re-election prospects.

2. Risk Factors and the Remaining 30% Probability

The remaining 30% probability accounts for risks primarily associated with a failure in coordination among the Elders or an unforeseen surge of organizational support for an alternative candidate.

• Risk A: Breakdown of Elder Coordination and Conservative Backlash: If strategic conflicts intensify between Aso and Suga, causing the Elder vote consolidation to fail, or if Diet members fear a massive conservative backlash in the next general election and begin systematically voting for Takaichi, Ms. Sanae Takaichi could achieve an upset victory in the runoff, capitalizing on her momentum from the first round.
• Risk B: Unexpected Surge and Victory for Yoshimasa Hayashi (5%): Should Prime Minister Kishida’s influence persist unexpectedly strongly, resulting in a critical mass of ex-Kōchikai Diet member votes consolidating behind Yoshimasa Hayashi—in defiance of the broader Elder coalition’s risk-minimization strategy—Mr. Hayashi could win the runoff. Given his low national appeal and the strong logic of Elder rule, this scenario is assigned a limited probability (approximately 5%).
• Risk C: Overwhelming Party Member Victory for Takaichi: If Takaichi secures an overwhelmingly large majority of the party member votes in the first round, she might generate sufficient momentum to attract skeptical Diet members. However, the 2024 precedent suggests that overcoming the centralized opposition of the Elders in the runoff remains extremely difficult.

The convergence of structural advantage, historical precedent, and the Elders' political self-interest strongly suggests Koizumi's victory as the most rational and likely outcome for the 2025 LDP Presidential Election.