What if someone wrote “kids” Japanese books following common folklore (not needing to make up something new) for each level (or set of levels) that utilize only the kanji that has been learned so far. You could use hiragana or okurigana for kanji that isn’t yet known.
The books could consist of an image on each page + some text.
That way we could actually use the kanji we learn, and when we level up well beyond the kanji we’ve already learned, we’d keep seeing it and wouldn’t forget it. It could also be a further point of memorization similar to the mnemonic system.
You could unlock the books as you level up as ebooks and optionally sell physical books too? it would be a great achievement item for us users and a point of pride when we see them sitting on the coffee table. A huge stack of books for all the kanji we’ve learned
There are lots of graded readers available these days. I have the sentence books made by the JapaneseAudioLessons website. I also use Amazon/Kindle for the Kanji Learner’s Course Graded Reading Sets, the first one is free. I also like the readers put out by TheJapanesePage and they also do Makoto which is a monthly zine with a small reader section. A lot of people prefer Mangajin which you can find online for free. The White Rabbit ones that have level 0 (and cost a fortune but are available to some in schools/libraries) are now available through an Android app for a few dollars a story. They are probably the best for getting started if you don’t mind kids stories. There are some other more advanced ones on Amazon as well and then there are other resources like Satori reader and Moe Moe. Plus the book clubs on here.
The app Satori reader is also pretty cool. It has lots of short stories and articles with translations and the ability to click words and phrases to get their meanings and add them to study lists. Depending on your settings, it either shows words you don’t know the kanji for in kana or with kanji and furigana. You either choose a certain kanji level, or you can connect it to Wanikani with your API key.