Assuming you obtain a legal copy (physical or digital), here is a step-by-step study method that maximizes its value:
Chuukyuu e Ikou: Nihongo no Bunkei to Hyogen 55 (Getting to the Intermediate Level: 55 Japanese Sentence Patterns and Expressions) is a textbook published by 3A Corporation designed to bridge the gap between beginner and intermediate Japanese study. Access and Resources chuukyuu e ikou 55 pdf