Are books out of the question? I feel like those would be the thing to read when you want to read. What kind of stuff are you interested in?
Japanese Language
ようこそJapaneseLanguageへ! 日本語に興味を持てば、どうぞ登録して勉強しましょう!日本語に関係するどのテーマ、質問でも大歓迎します。 This is a community dedicated to the Japanese language. Feel free to come in and ask questions or post your thoughts and opinions about this beautiful language.
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I don't know where I can get a hold of books for free, but I would say books about Linux/OS. Maybe something about linguistics, or something written about Japanese learning in Japanese (by a native speaker). I would definitely read something similar to Lemmy or Reddit in Japanese.
You can checkout misskey.io
From my experience it's just a Japanese Mastodon. It's also part of Fediverse.
Apparently they don't allow VPNs :(