These do not replace the textbook but can supplement your learning.
Here is the hard truth:
For decades, the series has been the gold standard for serious Japanese language learners. If you have conquered the red (N5) and brown (N4) books, you are now staring at the next big mountain: the Upper-Beginner to Intermediate level, commonly aligned with the JLPT N3 exam.
The content is meticulously divided to cover the four pillars of the JLPT:
Expect to pay approximately $30–40 USD for the digital main text, and $20 for the grammar notes.