Apparently this film was shown in a BBC 4 season called "Why Democracy?", introduced by the question, "Can politicians solve climate change?" But this is clearly not a heavy serious-minded documentary. And there is no mention of climate change. There is barely any mention of political issues at all.
I don't think the director was making a great effort to raise "issues" or make serious "points". And I am sure he was not trying to make points that are relevant in all countries. Not all themes are universal. Many of the quirks of Japanese democracy result from the country's laws and are therefore probably unique to Japan. I think the director just made the film like this because he thought it would be interesting, funny, and entertaining.
There are many extremely funny scenes: the station staff jamming people on to trains; Yamauchi throwing his socks into the corner of the room, into a box of newspapers; his friends saying that he hadn't paid social insurance (this is an issue that has led to the downfall of several senior Japanese politicians).
There are several scenes that make you think, "How on earth did he get permission to film this?" And it is an impressive film in that way. But as you can see from the other IMDb pages, the director did the producing, photography, and editing himself, and he knew the candidate from university. I am sure Yamauchi would have been much more wary if a big crew from a major TV station had turned up and tried to film private conversations with his wife. But in the end all the main characters come across as good people.
I suppose you could say that Yamauchi is uncharismatic. But that is not a crime. He is just a person trying to do something. And after all, this is only a city council election.
The ending was slightly unsatisfying. When everyone else was in the office awaiting the result of the election, Yamauchi was inexplicably still at home. And when he finally arrived, he somehow did not seem to be himself. And then it was all over.
--- USEFUL THINGS TO KNOW BEFORE YOU WATCH THIS FILM ---
(I agree with the previous comments that audiences who are not familiar with Japanese politics might find this film difficult to understand.)
Japan has very strict legal restrictions on how candidates are allowed to campaign. This explains why he does not use radio or TV to campaign, and why he has to start and stop campaigning on the streets at certain exact times of day.
In Japan, many people vote for the LDP unquestioningly. They are just conservative-minded and they prefer things not to change. This goes part-way to explaining why there is almost no discussion of issues and the whole campaign seems to be just an effort to get people to know the candidate's name.