🍃 Shenmue Tree - a Study "Lounge!" 🍂

In addition to the ruby tags mentioned, there’s also IME2Furigana

The only minor annoyance I have with it is there’s no way to have it default to off. If you don’t need something that automatically uses your IME, you could also go for the Easy Furigana userscript linked in that post. I might do that considering I only occasionally use it anyway.