I never asked if it would work. I asked WI some men in the JSDF answered his call for a coup?
Oh, sorry if I derailed the thread
These officers are purged from command, the public and the ruling parties are now paranoid about the Japanese Self Defense Forces, and so are the Americans.
If they hold that headquarters and perhaps some other buildings for a few days in 1970, they could create a real crisis, and Prime Minister Eisaku Sato and the LDP will lose or win popularity and power depending on how they deal with this.
Once surrounded by regular elements of the Tokyo Police and loyalist officers of the JSDF, Mishima gives his speech and commits suicide, disappointing those who thought he'd lead the revolution.
If Mishima nevertheless allows this to go to his head and decides to fight to the end and die the death he thought he deserved in WWII, we could see a Waco style siege, but with the regular army, ending in many casualties, suicides and the loss of the headquarter if some decide to fight to the last man and others surrender.
The public could be polarized and shocked by the disaster, the Sato ministry fall in 1970 and be replaced by an earlier Tanaka ministry, if elections are not held and the public turns against a LDP now perceived as incompetent, if elections are called in 1970 or 1971, the opposition is unlikely to win, but say the crisis propels a ministry much like the one of IOTL 1993-1996...the Socialists are in power for some months, the minority government collapses as the US is somewhat hostile to them and vice-versa, etc.
Cultural effects of a known and popular author wanting to overthrow the government and the ensuing bloodbath would be harder to predict. Maybe the youths are more politicized, pro-Mishima groups appear throughout the 1970s and are seen as a menace by the public and the Government, the USA could funnel even more money to keep the LDP in power.
Extreme rightists following Mishima's example could engage in terrorism, giving the Japanese Red Army Faction a run for it's money, and emulate acts like the assassination of the Socialist Party Chairman of 1960.
A culture of security in which the JSDF take a different role in the late cold war could be an interesting effect.
Just a thought.