I started using this method during covid. When I started, I could not hold a conversation in Japanese too well (I would assume N4 level with 0 conversational practice), using pretty broken Japanese and stumbling quite a lot. However, in 2 years of doing this my spoken Japanese improved so much that everyone around me thought that I had been speaking Japanese all my life. I could hold conversations no problem, and it even helped me at work, where I would have meetings with stakeholders (of course, all Japanese).
The method is Gaming in Japanese.
Find online Japanese friends to play your favourite games with, and practice speaking in Japanese while having fun. You learn SO much slang, double meanings, internet culture, common ways normal people say stuff etc. It was a GAME CHANGER.
I found online competitive games to be the best for this. The core callouts can be learnt quickly (push, fall back, behind you etc), and you can slowly increase the breadth of your conversation during the queue times etc. Finding people to play with is also easier I think, just join the Japanese servers for your game of choice and talk in voice chat and make friends.
I started doing this at an N4 (this is an assumption), and now I think I can call myself fluent. Keep in mind, I did 0 "study/practice" other than this.
I also should add that I am a ハーフ, but was brought up aboard, so I never learnt or used Japanese. I had the pronunciation down good enough, but my language level was extremely low. So I did have an advantage in terms of being able to pronounce Japanese at an almost native level.
by Everlearnr