alt Hacker NewsNo. JP activity was always second to US, only the biggest "out there". Same is true for all Twitter-like social media, such as Mastodon and Bluesky. Even VRChat doesn't have a majority Japanese userbase. Japan actually becoming the top majority anywhere is an anomaly and a major reversal of power balance.
Still blows me away that Google had complete dominance in Brazil and then just threw it all away and shut it down a few years later.