Any leading party will face the deadlock in foreign relation and national security because of it.So you will have to make a choice whether to ignore constitution to certain degree to fit the needs in reality or stay away from the administrative power by keeping the idealism of article9
JSP and JCP could always pretend they are commited democrat for they obey the ideal of the ａｒｔｉｃｌｅ9 and respecting ｔｈｅ constitution, While LDP maintains power but gets canned by media and public opinion as no good quasi-democrat and would be militarist.

This impression is being summed up by accusation from foreign government JSP and JCP could cultivate political gains at the expense of LDP and perhaps national interest.which eventually escalate into political crisis.
These internal and external factor bring devided-we-fall-kind of weak ｐａｒｌｉｍｅｎｔａｌ order.Hence most of the works of the nation are run by the initiative of bureaucrat.
and the lawmakers simply follows them.

Bureaucrat ａｎｄ big corporation needed ally for stable and sustainable political order.which must have the ability of
a) coorperative to the interest group
b)taming both oppositons in and out of country.
for a) LDP established corporate state sturucture
for b) they kept article 9 untouched so the political rivals do not nake any fuss

JSP and JCP discovered they cannot outpace the holy trinity of LDP ,bureaucrat
and Big companies,they’ve settled with the agenda of goken護憲　selfproclaimed
guardian of the article9.and unofficialy abandoned the task of regime change. Pacifist supporters agreed to this passive perticipation to parlimental democracy.

P.S
I KNOW I’,m overly simplifying

Ｂｒｙｃｅ：
Ｉｔ’ｓ me you’re talking to ,not Marxy，Ｉ think.And Ｉ thought what you’ve asked was whether marxism was a key to J-academia.and my answer was,yeah it was until 1970.Oｎ others, Ｉ totally agree with you.

M-Bone and Mutantfrog:
I’ve been thinking Macarthur constitution(it ain’t ＰＥＡＣＥ costitution for me!）was partly guilty of creatiｎｇ defacto one-party state of post-war Japan.Think of Meiji constitution.I don’t have accurate number but back then there were more frequent regime change than post-war period.This is one of the reason I want to have constitutional revision.

I can totally believe that a majority is in favor of constitutional revision in some fashion, but are there any specific proposals that have wide support? Or is it just a matter of “we should have a constitution that wasn’t translated from English, I guess.”?

People who inhabit modern Japanese universities do not embrace Marxism as enthusiastically as in past times, but that does not make them any less ‘academic’.

As for the notion that Japan’s radicals are still not ‘dead’, the only evidence I’ve seen supporting that view lately is a few old ladies waving signs around Nagatacho. I might well agree with you that Abe will face an uphill battle if he wants to change Article Nine, but this will be due to what Glenn Hook has referred to as an ‘embedded norm’ of pacifism in Japanese society. The marxists may have played a valuable role in promoting and popularising that norm during the early postwar years, and the norm still remains, but that doesn’t mean to say that Marxism itself is anything to write home about in modern Japan.

Back in the days there were times that marxism WAS a prerequisite
of a sort to get a tenure in Japanese universities.

Remember Prof.Fujioka of notorious TSUKURU-KAI,Japanese Society
of Historical Textbook Reform was a card carrying member of JCP
before he became born-again right wing?and Nishibe Susumu was
an activist of BUND?Even the right among the rights were once a marxist.

Marxist did have strong touch with the reality in early stage of post-war Japan
because
1)In developing country ,marxism sometimes give more satisfying analysis
on socio-economic issues and were taken seriously by decision makers.
best and the brightest in Tokyo Univ.of 20’s and 30’s were marxist.

2)Since marxist were oppressed in 30’s and 40’s.They achievd status of “righteous” intellectual in post-war,compared to war collaborationist conservative or liberals who couldn’t fight all the way.Seeking the war-responsibility among professors had been popular pastime for students and being marxist was the easiest way to avoid humiliation or disguise your true colors.
As well as in schools,marxist ideas filled newspapers and magazines whose circulations are unimaginable scale in other countries,which affected generations.
(this would take us back to media immersion to the society debate)

3)They were anti-american,So they could conduct mass demonstrations
and strikes around U.S bases.or on occasion like extinguished Ike visit,
security treaty revision during Abe’s grandpa and war in Vietnam.

These reason gave more or less a leverage to reality for marxist in ivory towers
before 1970.

And don’t you forget .”peace constitution” is still standing firmly on political
horizon despite the ongoing talk of revision,a political objective Japanese left had been persisted for last half century in return of the idea of holding power.
They may be down but not dead yet.