Tobira: Gateway to Advanced Japanese
Tobira is one of the most often recommended Japanese textbooks for pre-intermediate learners in communities like /r/LearnJapanese for good reason. It is a great book with very useful grammar explanations and examples which themselves use grammar points previously learned. The essays contained in the book are interesting and not overly difficult.
Also, the accompanying official website offers extra resources like audio and even pre-made Anki decks! It’s very convenient, and it would be even better if the decks contained example sentences as well instead of isolated words.
This book definitely does not hold your hand with English translations and it feels like a shock to many students who recently finished Genki II, and rightly so. But if you bear with the initial discomfort, you’ll see your Japanese visibly improving.
I have only two main problems with it: the grammar notes section is way too far away from the reading material, which is a nuisance. Also, the vocabulary list sometimes contains words that are too basic and some more complex expressions used in the texts don’t make it into these lists for some reason. Apart from that, it’s a great book and I feel fortunate to have stumbled upon it. Don’t let the lack of English scare you, embrace it!