Advanced beginner level or Level 4 of Japanese Language Proficiency Test (JLPT) with about 1500 to 2500 characters. These books add 150 words of vocabulary to Level 0 and 1. Also, the grammar is less controlled than Level 1.

Grammar
dictionary form, て-form, ない-form, nominal modification, ～と（conditional）, ～から（cause）, ～なる, ～のだ,　etc.