You're right. Japan's population pyramid is inverted [1]. Personally, I wouldn't call the rate ever more rapid— it's seems quite linear given that fertility rate has been pretty steadily around 1.3 since the 90s [2], but it is definitely still shrinking.
Russia's population pyramid does seem to suggest a big dip once the generation born in the 80s passes away, but it doesn't look like a reversed pyramid just yet. The generation born in 2021 doesn't seem considerably smaller than the one born 20 years ago [3].
