I am not a reference at all but maybe that I can help.
I love the VN format since you have all the time you want to translate, you have voices (most of the time) and it has a story so you actually want to understand. (BTW, I learned English thanks to this)
Firstly you need to at least understand the basic of the grammar, enough to be able to translate a sentence using a website like https://jisho.org/ (I use it all the time when playing Japanese VN), by basic I really mean the basic, reading grammar guide during 5 hours would be horrible. You can try to find a simple VN and read it at your own rhythm, you'll end by finding some grammar patterns by yourself and get some automatism.
Kanji are important, I do have an iOS app called "Kanji!" which uses flashcards and have a writing exercise. But most of the time you'll use Jisho since I cannot really ask you to learn 2000 kanji before starting reading anything