In brief, Adelstein argues that after decades of deep ties to the LDP — which organizations didn’t have deep ties to the LDP when it was Japan’s hegemonic ruling party? — leading Yakuza organisations have shifted their allegiances to the DPJ as it took control of the upper house in 2007 and then the lower house and with it the cabinet in 2009.

The main consequence of this shift, Adelstein suggests, is that the Hatoyama cabinet included Kamei Shizuka, head of the People’s New Party, who is known to have links to organised crime. Without questioning those links, I think there is a far simpler explanation for Kamei’s presence in the Hatoyama government, an explanation that does not require any reference to the Yakuza. Wanting to streamline decision making in the new coalition government, the DPJ included both Kamei and his SDPJ counterpart Fukushima Mizuho in the cabinet and created a special cabinet committee to coordinate policy among the ruling parties. Kamei, I think, was there so as to concentrate coalition negotiations within the government. The ease with which Kan Naoto cut Kamei loose once he challenged the new prime minister suggests that repaying the Yakuza was low on the DPJ’s list of priorities when it came to Kamei.

But this case raises the larger question asked in the title of this post: what does the Yakuza explain anyway? What political outcome over the past half-century or so of Japanese politics is different because of the influence of the Yakuza in Japanese politics?

The most obvious answer is that the pervasive influence of the Yakuza explains the impunity with which gangsters have been able to act since the end of the war (which makes the 1992 anti-organised crime law mentioned by Adelstein a puzzle worth explaining).

But what about bigger questions? The durability of LDP rule? The rise and fall of prime ministers? Foreign policy and relations with the U.S.? What is different because of the Yakuza’s power? What can the Yakuza explain that other theories cannot? I suspect not much. It’s possible that gangsters may have influenced the outcome of LDP leadership elections during the former ruling party’s heyday, given the shady pasts of some leading LDP politicians and the wholly opaque manner in which the LDP selected its leaders for much of its history. If it were possible to identify prime ministers who came to power only because of Yakuza support, it would perhaps be possible to identify indirect consequences of Yakuza influence, but as Adelstein’s own career shows, becoming a Yakuza expert requires time, energy, and no small risk to one’s person — all for exploring what may be nothing more than an auxiliary explanation.

That’s not to say that the Yakuza are of no interest to political scientists who study Japan. One question worth addressing is why the Yakuza are so pervasive in the first place, at which point attention naturally turns to Italy, that other Axis power occupied by and then allied with the United States (which failed to purge and in fact developed links with far-right elements) and governed by a hegemonic conservative party for the duration of the cold war. Additionally, it may be fruitful to study the Yakuza in comparison with other interest groups that had long supported the LDP only to watch their fortunes wane during the lost decade(s). After all, Yakuza groups are interest groups, of a sort: interested in the regulation of organised crime. Like other interest groups, they had to adjust their political strategies in response to uncertain political and economic environments.

As such, while the Yakuza are an unlikely explanation for major political outcomes in Japan, they are a part of the landscape and observers should be cognisant of their role. For that we are lucky that Adelstein is working so hard to expose the inner workings of Japanese organised crime.