Preface:
Crazy long, sorry if its more than you bargained for. I promise its all related 
Due to wanikani being geared towards learning kanji and vocab, most discussion revolves around getting into reading (or the JLPT) and Iāve never really had the chance to fully dive into what my experience has been like learning japanese these past 3 years trying to bridge the gap between my japanese and a natives beyond just reading comprehension. The past 2 years especially have really solidified my core view towards achieving and operating at a high level in Japanese (or any foreign language), especially when it comes to output.
Before I go into that, what I did, and how that experience shaped my opinionsā¦disclaimers. Firstly, my experience learning Japanese was abnormal. I started speaking and reading after being literate in the language. I had read 70 books or so (not even counting other mediums) before starting and had maybe 6000 hours of dedicated study time. Secondly, this is from the perspective of someone who wanted to get as good as possible at the language and is pretty hardcore. I donāt necessarily suggest anything be replicated universally. For a very small subset of learners I think some of this stuff might be good to consider or try out depending on where they are at in their journey and their goals. Thirdly, this is my own personal experience. I donāt want to have to preface everything as such, so just take everything as my own personal opinion.
The meat:
So Iāll go ahead and say the most important thing I realized first so that way when youāre reading my experience and process I can highlight how I arrived at it. The biggest āsurpriseā or ārealizationā I had was that past a certain point, my native language became a very big (possibly the biggest) hurdle to my ability to output and think in Japanese. I had always thought that fluid Japanese performance was solely reliant on how much Japanese language I acquired, but it was also heavily dependent on my ability to disconnect from English. So anyways, what did I do that caused me to arrive at this conclusion and where did I go from there?
So all of my reading practice didnāt amount to much output ability (though it was an insanely helpful foundation). I was absolute garbage. But I have found that listening actually did help my output ability significantly, so Iāll start from there (though keep in mind I didnāt start from 0 and had my foundation). So I was listening to primarily audio books at the start because I found them great for my specific situation and also dabbled in some éč« for awhile. I wonāt go into the details on how I improved listening specifically, but I got better. Then a very special thing happened. I decided one day that I was going to listen to an audio book for a few hours straight. I had been watching anime prior to that. When I was listening to the audio book though, I was like super intent. I blindfolded myself, leaned back in my chair, and had my fingers on my keyboard to rewind 10s anytime I missed something. Super focused activity. Anyways I did this for maybe 2 or 3 hours. At that point I took a break and put my headphones in to listen to a playlist of japanese music I had been listening to for maybe 5 years at that point. I distinctly remember getting up to go to the bathroom and having a āwhat the fuckā moment. I had been in the habit of ignoring japanese audio from my history of reading focused study, but especially for music I didnāt listen to lyrics much. I had this playlist for 5 years but I couldnāt have told you what the lyrics were to the song I was listening to. Until that day, at least. The lyrics were so blatantly clear to me and despite me not trying to listen to them and being focused on someone else, after a few seconds I realized I was understanding all of it (for the first time) with no particular will to, just like would happen with my native language. I had also listened to that same song probably just a week or two earlier without understanding anything, and the language of the song was not difficult at all, so the difference in understanding clearly had nothing to do with language skill. It was some weird unconscious setting in my brain where it was just set to listen to and parse japanese by default (similar to how my native language is).
That was a relatively isolated incident, but youāll see it fits a common theme. Continuing on, I decided I also wanted to practice output specifically a bit more. I had done a bit up until that point but it was like really weirdly influenced by my reading and the most recent words I had learned (which were almost all rare) and my output was pretty unnatural. Anyways, with more listening practice under my belt I went for some more proper practice. I started typing up a diary type thing where I would just answer random questions I came up with or talked about my day. I even posted it for corrections on a language exchange site. I quickly realized that people tend to use similar expressions over and over again so if I could just get a handful of the most common ways I like to express thought down, it could have a very large impact. Long story short, I did that. From all my listening practice I also started to have a āvoiceā in my head where I could kinda have the language I wanted to use pop up in my head from all of the input I had up until that point. I also had an issue where I would have like a fragment of something pop up and my brain would get stuck on this sort of ātip of my tongueā scenario. What I did to solve that was actually have a collection of all the books I had read up until that point in sublime text and essentially use the search tool to scan all those books for certain patterns until I could find the one I was looking for. This actually helped significantly.
All this+listening+outputting at work every day actually got me to an alright level over the course of a year or so. However, I felt like while I had the ability to construct proper japanese, I was rarely able to fully use it. I could type out a sentence, look back, maybe re-word it and fix it, and be 99% confident it was grammatically accurate but when you actually speak you donāt get that luxury. I also realized I had a tendency to drive myself into a ādead endā when speaking. I would start sentences off in a way that might make sense in english, but part way through would realize that I was unable to fully convey the thought I wanted to because of word ordering. Like for compound sentences, in japanese you might need to start the sentence off one way but I had started it off with a different thought or used a certain particle or something that limits what I can say after that. So what I did for more practice was essentially write my thoughts in a diary but not give myself the ability to use the backspace button. So if I wanted to express a thought and kinda drove myself into a corner with wording, I would have to work my way around it in real time. Also if I didnāt know how to express something, rather than stopping to think about it or look it up, I would just find my way around explaining it.
All of that resulted in me being pretty good at constructing correct and fairly natural japanese pretty fast (as fast as I could type) in my head. But something about it still didnāt fully feel like āthinkingā in japanese. I mean, I was thinking in japanese. But something about it felt like some very deliberate cognitive process. When I type in english it almost feels like the thoughts just kinda pop up and I type them out. Here it literally felt like I was āconstructing japanese thoughtā as opposed to āhaving my thoughts be in japaneseā if that makes sense. Close, but still a bit different. Many learners will be more than content with the ability to fluidly construct natural grammatically correct thought in japanese. Thats perfectly fine,but for one reason or another I personally want Japanese to be as close to a second native language for myself.
And thatās when I stumbled across the dark arts (well, they were at around the same time actually maybe). I noticed a very interesting phenomenon when I would maintain a particular schedule. When I would read minimal or no english, speak no conversational english for prolonged periods, and listen to Japanese in virtually all of my freetime, especially before bed, I would have a pretty high chance of dreaming in japanese. And if I continued that for a couple days, I would typically enter what I call ājapanese modeā. In japanese mode it felt so much more effortless to listen to and produce japanese. Not only that, but I was able to talk a lot faster, smoother, and naturally. I also had a lot less of an issue with running myself into a corner with constructing sentences. Talking with my parents or someone in english for 30-60+ minutes though would usually be enough to get me out of this mode.
Around this time I talked with one of my AJATT 大å č¼© about this. This individual had been studying for far longer than me and was far more hardcore, so I picked his brain about listening practice and natural output and was very surprised to hear that he also arrived at the conclusion that input from english can cause problems with āfeeling outā output, word worder issues, and that japanese people even have a word for this ęÆčŖå¹²ęø (apparently we do in english too). He told me that while maintaining japanese environments are still required even for him to maintain his peak level, the amount thatās required to enter japanese mode, and how easy it is to fall out of it change (favorably) the more experience you have under your belt. He also mentioned that passive listening was good as a way to maintain ājapanese head spaceā as opposed to the other benefits people often mention for passive listening which he felt had diminishing returns past the first couple years. I was interested. This sounded like what I needed to help maintain my japanese mode.
And with that we got the final piece of the puzzle. At this point I was regularly listening to éč« streams and got a setup to where I could just listen to old ones at any time while doing something like walking to the conbini. I have a tendency to think a lot in english, namely by sort of imagining conversations in my head, but I noticed that it was very difficult to do so with my passive listening tracks on. It was like a jamming signal for english. And the result? I was able to maintain my japanese mode much much better. With japanese mode it felt much more effortless listening to japanese (and thus fun), and my japanese output felt so much more effortless. Like I was actually just thinking in japanese and saying the thoughts as they came up. It was a lot more like I had envisioned and my goal was to maintain it and get as much practice smoothly outputting in japanese mode to speed run making the connections in my brain that I wanted to make.
Piece of information that will be relevant later: I was usually playing rocket league with leebo on friday nights and calling my parents saturday mornings, so I would watch english and youtube and stuff I wanted to watch on friday after work since I knew I would be out of japanese mode anyways. This meant that I never really had to speak much english in japanese mode, and when I did it was usually with a friend who I could use a lot of japanglish with.
Anyways, that continued for a few months but due to life stuff I took up studying something that would require me to read a lot more english and have less input time. I reluctantly went back to maintaining a much more normal routine, but felt like I had made serious progress to where even my default state was significantly better at outputting japanese. Like that time in japanese mode was just hyper-efficient at getting me to improve in the language. And that makes sense. More effortless input = higher levels of comprehension, less getting tired, and more enjoyable so I naturally focus and do it more = lots of strengthening connections in my brain. As of recently Iāve actually had more ä½č£ though, but it was hard to go hermit mode since I had a buddy going through some serious issues at the time. That got resolved and then a couple weeks ago we actually had a party with my coworkers. I did fine output wise, but I felt pretty lacking listening wise since it was in a comically loud izakaya. 1st semester for school was also finished so it was perfect timing to go back to hardcore mode. I went back to ālisten all the timeā mode, and as you can guess, I entered true japanese mode for the first time in a while really.
Enter āwhat the fuckā moment #2 and #3. #2: I had been listening as usual and I got up to take a shower one day. I usually kinda have these internal monologues in the shower (hopefully Iām not alone), but I noticed that day my monologue was in japanese. I kinda tried to switch over to English, but it felt very weird. It literally felt more natural for me to think through an internal monologue in japanese in that moment. Needless to say my output was also on point. It felt so much more effortless and smooth. What the fuck moment #3: I called my parents on saturday as usual, but I hadnāt played rocket league with leebo or watched english youtube the day before. So I woke up, listened to japanese for a couple hours, and then made the call in japanese mode. It might be hard to believe, but it actually felt more difficult to speak english than it would have to speak japanese. At least for a majority of the things I was trying to say. Not only that, but I had the exact same phenomenon where I was expressing thoughts with the japanese word order and getting stuck in english. Put lightly, I was tripping over myself in my own native language.
That was a true moment of confirmation to me that regardless of my actual potential skill in the language, my brain has one language its adapted to at any given time. I can increase the speed at which I adapt, or how long I stay adapted for, but Iāll be adapted to one. I can still speak the other but it will be like swimming against the current vs swimming with the current.
And with this, you can really deduce/see all of my opinions towards getting to the level where you can naturally just think in japanese. First, just as a matter of common sense I think you need to get to the point where you can construct japanese thought. For this, I personally relied on a lot of input followed by a lot of practice oriented output and corrections as well. Some people will claim input alone is enough but that has been a load of bullshit from all the good people Iāve actually encountered. Then, it was a matter of cutting english out to get my brain out of default english style thinking patterns and then listening to a bunch of japanese to strengthen that voice in my head. These two are of course done with the same step of just mass input.
Part of me does wonder what would have happened if I cut english out earlier. I realize now that probably a very big benefit of doing āAll Japanese All The Timeā in the literal sense isnāt just the fact that youāre spending so much time exposed to the language. Its probably also the fact that youāre spending so little time with your native language. Not sure when its optimal to start, but it definitely felt like that component was a major step in finally feeling like I could just have my thoughts/internal dialogue be in japanese. Itās certainly not a goal for everyone, but I can say it brings about a level of effortlessness with using japanese that just feels so damn great.
In summary: I first learned to construct thought in japanese fluidly in a way that felt more like a deliberate task before taking the leap before it just felt like an unconscious/effortless process. In order to get to the fluid construction I relied on a lot of input (especially listening) to create a sort of guiding āvoiceā in my head, outputted via writing focusing on corrections to tune that voice, outputted via writing focusing on making no compromises in what I want to say in ātip of my tongueā situations (which often involved a lot of looking up), and then finally outputted via writing focusing on just long streams of thought and high quantity with no stopping in that order. This was while using japanese everyday at work, though I personally donāt think that was as helpful as you might suspect. I started to feel like I was hitting a bit of a wall, but then once I significantly cut out english, I was able to then achieve a sort of āheightened stateā of ability temporarily that I would study in and try to maintain. This heightened state was able to put me in a fully japanese mindset and free me from English habits while making output (and even input) feel much more effortless and natural.
This got crazy long. Hopefully this answers any question you might have (and more) about me getting to this point. I skipped over a lot of specifics on listening practice. Heres a post from a little over a year ago where I go into more detail on some stuff. I refer to japanese mode here as a āheightened stateā.