To grow your active vocabulary, you… have to output. Can input help with that as well? Yes, somewhat, but only insofar as it provides you with models for ‘good’/natural output. It’s really a matter of learning how other people say things and getting a feel for how you ought to say them in order to be understood. Honestly, I think it’s a lot more valuable if you remember phrases or sentences. The point isn’t to recite lines, even if you can work with that if you enjoy doing so; the idea is to have a mental database you can check yourself against.
You can definitely use stuff in the EN->JP direction like Kaniwani or Kamesame, but the issue with that is essentially exactly the same as learning vocabulary via WK alone: you aren’t required to recall or understand the context in which something is used in order to answer correctly during reviews, because you’re just translating keywords.
What I’d recommend is to go look for memorable input that you want to recall. Go look for Japanese content that you’ll be happy to look back on, whether it’s a podcast, an anime or a magazine article. Pick out phrases and sentences that pique your interest and study them (i.e. figure out what all the words are, work out the relationships between them and decipher the overall meaning of each phrase/sentence), and memorise them if you like. The ideal is to pick sentences that are linked to a really emotional or striking moment so it’ll be vivid. After that, well… review them with an SRS or notebook if you need to, but if the scene was that impactful, you’ll probably think about it spontaneously. After a little more study of how to use that phrase… voilà, you’ve got active vocabulary. Why am I recommending this? Because I think that until we build a habit of using a word ourselves, we rely on inspiration in order to use it.
Some examples (most of mine are from anime, and just for the record, I don’t use an SRS – I do revise, but not on purpose, and I’ll explain that in a bit):
- 「うううう！忌ま忌ましい！」: this word means ‘irritating’, and this phrase is taken from The Rising of the Shield Hero in a scene where an antagonist is frustrated by the protagonist’s success in a race (I don’t remember all the details, but I remember the race, how the antagonist tried to secure a win, the characters, and I can hear the antagonist’s frustrated voice as I think back on this)
- 「貴重な薬を…てくださいました」: another one from Shield Hero. Can’t remember the whole phrase, but it meant ‘He gave[keigo] me valuable medicine’. The scene? The deuteragonist making a spontaneous speech in defence of the protagonist after a forced duel while standing in an arena. Struggling to remember that 〜てくれます becomes 〜てくださいます in keigo? Well, you won’t after hearing this speech – it’s just 〜てくださいます over and over and over again, with tons of passion. It also helps that the speech starts right after a resounding slap.
- 「ぱくぱく食べる」: I’m not 100% sure this was the sentence, but it was something to that effect. The phrase means ‘to eat heartily/voraciously’. This one’s from season 1 of Quintessential Quintuplets. I’m not entirely certain of the context, but I’m pretty sure it happened in the school canteen, and if you know that one of the quintuplets has quite the appetite… it’s easy to remember. I know I wrote the word on a folding whiteboard to remember it, and I believe I used a red Pilot V-Board Master to write it (had to look up the model name, but I can see the marker in my head).
- 「どう？頭いいでしょ？」: this one’s from Konosuba. ‘How’s that? Aren’t I smart?’ Basically any time the goddess in the main cast has done something she’s proud of (which typically ends up being the cause of another disaster), she says that. It’s a shortened version of 頭がいい, literally ‘head is good’ i.e. ‘having a good head on one’s shoulders’ = ‘being smart’. It’s so much of a flag in the story (it sets up tons of jokes and catastrophes) that there’s no way you won’t remember it. The goddess also always says it the same way, with the same sort of expression, so it really sticks.
I think you can tell from the way I describe all this that my memory is pretty good to begin with (in the sense that I clearly vividly recall a lot of circumstantial detail, including how I learnt the word), so perhaps this isn’t something that will necessarily work for everyone. However, I think we can agree that many – maybe even most – of us remember certain phrases or scenes for being really impactful in our lives. This is just an extension of that.
Now, as for how I revised… in this particular case, it just so happens that I really loved most of these anime, so I used to watch them on repeat. Quintessential Quintuplets is the only one of the three I’ve just mentioned that I only watched twice; Konosuba and Shield Hero are anime I’ve watched… maybe five times each. At least. However, the point wasn’t revision – I was just having fun. Still, I did try to pay a little more attention to the words used each time I watched them, because I really wanted to learn more words.
In short, what I’m saying is this: short of doing output practice – which isn’t always productive, depending on how you do it, especially if you’ve got no guidance – you can also focus on acquiring vivid memories of specific phrases that you can then
- Imitate and reuse
- Use as models for natural usage by extending how they work
That brings me to output practice. I’m not gonna bother with a long explanation this time – the best option is getting someone focused on helping you learn to encourage you to say/write things and then correct you – but I will say this: if you don’t have a teacher – and I didn’t, not for three years, unless you count my friend who occasionally checked my sentences, and I frankly didn’t ask get much feedback from my teacher in my fourth year of Japanese – then what you need to do is to study examples. You need to go into output practice asking yourself, ‘How can I say this naturally?’ and then check how people actually say similar things. Don’t expect literal translations to work, especially for idioms; look out for equivalent phrases or general ideas instead. What you can use for this are sentence databases and dictionary example sentences from sites like https://ejje.weblio.jp and Jisho.org, as well as translation suggestions on HiNative and DMM Eikawa (this is a Japanese site for English learning, but you also get lots of questions on how to say something in English, or what an English phrase means in Japanese). Observe how other people use phrases, then do something similar yourself. Sometimes you’ll be wrong (e.g. I incorrectly inferred while writing an essay in Japanese that armed conflict could 暴れる – roughly ‘act violently; run rampant’ – since storms and natural disasters can), but most of the time, it works.