My friend is looking for a resource to become fluent in French, he is forced to work with it. Asked to find a certain book, but it is not yet pirated on the resources of the wiki. My guess is that pirates have better alternatives for such a thing, so I’m launching a discussion.
I only ever heard about the book “Minna no Nihongo” in the context of learning Japanese.
I learnt French through textbooks and then once I had a good grasp of grammar, reading French children’s literature with a dictionary. I don’t know if that’s the “best” way, but it worked.
Fwiw I mostly learnt English by just reading English books and not having a clue what was going on for a couple years but eventually got it. However I was a young child when I did that, so my ability to learn new languages was much better. I could probably do the same as an adult, but it would take me a lot longer. Don’t underestimate the brain’s ability to learn even without direct “teaching” like a textbook gives you.