ReadNihon is a Japanese Reader, similar to Japanese.io or Tenjin Reader, but the focus here is accumulating vocabulary that you can study later—a noble goal that will help any Japanese learner, if they stick with it.
When you have trouble reading Japanese text, paste it into ReadNihon's "Simplify Text" feature to add furigana and mouseover dictionary support. You'll also get an auto-generated vocabulary list and multiple-choice quiz based on your text! The vocab list lets you add problem words to separate study lists, which you can review as flashcards later.
The focus here is accumulating vocabulary that you can study later—a noble goal that will help any Japanese learner, if they stick with it.
ReadNihon has a lot going for it, and there's a solid foundation here that will hopefully lead to better and better results down the line. Because the simplified Japanese text is procedurally generated, as are the vocab lists and tests, results may vary—both articles I pasted into ReadNihon got cut off at about 500 words or so, and I found furigana above katakana stuck around until I set my reading level to "Advanced." Without SRS or export features for the flashcard system, you'll have to brute force your way through whatever vocab you study too.
Give ReadNihon a try, but also give feedback. There are solid features, and the goal of vocab accumulation through reading is exciting. In time, ReadNihon could become a top-flight Japanese Reader.