Yeah opposition parties have been really rough. A vast majority of them are conservative with only 1-2 ones that could even be called reformist liberal. Japan has the oldest unmodified constitution in the world. It's constitution was also modeled after America's and it's a prime example of why adding more parties doesn't fix anything. It's such a gridlock and even with the recent election getting a majority with one party, which has rarely happened, it's unlikely to actually result in any meaningful change like constitutional amendments. Japan is really built for "status quo"