By a lot, you should also clarify that out-spoken ones are high in number in general, as in individual people. That being said, they hardly represent the majority in the scope of the entirety of Japanese politics.
That being said, with the exception of the Democratic Party taking power briefly, the LDP has a stronghold in japanese politics and they include the most individuals withextreme opinions, but hardly anything controversial when you consider it from an international standpoint in terms of extremes.
You have to understand that when things are getting extreme in Japan, you have to compare it to other countries to realize just how docile the entire scene is.
People focus on Japanese Nationalism based of the understanding of nationalism in their own country, and that's simply not the correct way to assess Japanese nationalism.
As an example of this, Japnese politics STILL can't agree on whether education should be accompanied by rest of the national flag and national anthem. These are complete nonsense-issues in most countries like the US, South Korea and China where they happen with no issues.
If Japanese politics is getting "spicy" (spicy being an analogy for bad just for this example) people get riled up because it's Japan, but fail to realize that Japnese politics is doused in extreme levels of sugar and starch, making things very muddled and inefficient but also very mild. Whereas other countries are criticizing Japan while their domestic situation is already surpassing habanero level.
This isn't an excuse for Japan as much as trying to highlight that if you live in Japan, you realize that the crazies over there are no better than the Florida bible guy, Westboro Church or the Neo-nazis in Germant or the US. Yes they exist, but they hardly have a supporting population for that kind of activity also.
Lastly, I have to put this in too but if you study Asian politics and history long enough, you'll realize most other countries actually demonstrate consistently throughout modern history that they're not interested in knowing facts of history as much as perpetuating their respective victim history, often with grave exaggerations.
I wanted to become an Asian history expert but honestly am discouraged because I don't know if any country in east Asia is ready to fully accept the reality of history. This obviously includes Japan, but Japan is the most free of all Asian nations and there is no censorship over there in terms of content. You can't get away with that in China or even South Korea. You can be persecuted in South Koea for merely being descendants of collaborators with the Inperialist Japanese almost a century ago. Please google it, as I'm typing this from my phone. I can post sources later.
It's sad.