I’ve gotten into reading Japanese books a lot more recently, and I prefer e-books as their built-in dictionaries are a god-send for foreign language learners.
I’ve only used Google Play so far. The integrated dictionary is fine, but one annoyance is that it can’t detect any word that uses furigana. Are Kindle, Kobo, or any other platforms any better?
I read on a Kindle Paperwhite with these custom third-party dictionaries installed.
I also read on my iPhone and iPad using Immersion Reader with Yomichan-formatted dictionaries installed (I use a ton of dictionaries for better word coverage, both J-E and J-J monolingual dictionaries).
The advantage of using Immersion Reader is that you just simply touch the word, instead of selecting and highlighting it, so look-ups are quicker. Also in addition to installing multiple dictionaries, you can install frequency lists, pitch accent info, grammar guides, etc. When you look up a word, it’ll search through everything you’ve installed, so if you have pitch accent info and frequency lists installed, you can see the pitch accent of the word you touched, including the frequency number to help determine if it’s a word you want to learn.
Then you can save the word to your word list (it’ll also automatically save the definition and the sentence containing the word) so you can later export to Anki.
There also also third party tools that let you export your words from Kindle devices to Anki as well.
Note: some words with furigana may still be difficult to look up correctly on the Kindle and also Immersion Reader, if the formatting of the furigana is weird (a combination of the HTML code and the CSS styling). Sometimes the furigana isn’t clearly separated from the word, but instead jumbled together, so the dictionary may not be able to find the word.
Usually kanji-compound words are fine, but some words with kunyomi reading with a single furigana over it may cause some issues, but it depends on the book, and also it may depend on the particular word you are trying to look up.
To get around this, Immersion Reader has a search function that let you paste in the word (provided you copied it first), so you can fix the spelling (usually it means removing the furigana from the word) and it’ll search through all the dictionaries so you can add it to your word list. You can also edit each entry in your word list in order to manually add the example sentence, or to remove any unwanted dictionary entries.