I was searching for this earlier as well and basically no. Pretty much every forum I could find is either completely dead with one post every few days max, or it's a dedicated game/show discord/subreddit/twitter group or whatever that's mostly just zoomer memes and corporate accounts. A lot of good accounts and discussion on twitter, but it's twitter. It's not really a forum. It's mostly just japanese people posting pictures of their food.

This is probably more to do with the internet being about a dozen websites now than anything else. Many people have just given up entirely on forums and just sit in groupchats with people they know.