I know, but there would've been opposition to a state funeral regardless. The Japanese public perceived the state funeral and the decision-making process behind it as corrupt.

Here's a Japanese article from when the decision was made. Note that the scandal leading to his assassination, which was a significant issue in its own right, isn't even mentioned. That's because the decision to hold a state funeral was itself very scandalous.

https://www.nhk.or.jp/politics/articles/feature/89302.html

Also the cost of the funeral was 1.6 billion yen, which is definitely not "a few yen." It's crazy to think that taxpayers would be just fine with that.

https://www.yomiuri.co.jp/politics/20220921-OYT1T50164/