Thanks, Your detailed post is not in anyway incorrect regarding the problems with political systems in Japan, and explains very well the reasons why it is difficult for anyone but the status que to hold on to power, the population has not woken up.
Just going off the data that we have though current polls show you are actually more likely to vote left the older you are.
Support LDP the younger you are. This could be attributed to variety of factors like the only youth that vote are the ones that are pushed by parents, celebs etc along with all the disengagement you pointed out.
Obviously low voter-turnout etc means this is not the population at large, However I expect the rest of the youth population would
tell you they have no political opinion.
People over 65 are more likely to have grown up in left wing
University Protest period, when people were more politically awaken.
https://asia.nikkei.com/Spotlight/Datawatch/Japan-s-LDP-gains-more-popularity-among-people-under-40
JP link for the left poll
By Age group. Bright Red = LDP, Light Red = Komeito (LDP`S coalition party) Grey = Other, Light Blue = Nippon Ishin no Kai (Right wing party), Dark Blue = Communist Party, 2nd Dark Blue = CDP the liberal opposition party.