This grammar reference book is designed to help learners easily master N2-level grammar by covering 171 functional words and keigo (respectful language) in 9 weeks (45 days), with 3 to 5 items per day. The grammar explanations include translations in four languages (English, Korean, Chinese, and Vietnamese) to support self-study. Additionally, the book contains 520 practice questions to help learners reinforce and review the material they've studied.