Japan could rely on hydro - but the natural beauty of their country would be destroyed by dams (and there would be a lot less farmland). nuclear is really their only sustainable option. they could stop importing plastic - but buh bye tech if they do that, and that would crash, then erase their economy… and they are very deep into international debt as it is, so that will never happen.
the reality is that the Japanese have literally no choice but to maintain the status quo