Welcome to White Rabbit Japan!
As you gradually improve your Japanese, reading becomes easier and easier. But you will soon notice that as an intermediate student, there is a limit to what you can and cannot read. Many kinds of texts are still too hard. That's where graded readers come in: Nihongo Tadoku Books Vol. 4 is aimed at intermediate students at around the N3 level and gives you a sense of achievement for being able to read a book in Japanese without too much trouble. The 5 stories in vol. 4 are mostly about Japanese history, but there is also one story about popular culture (theater). The level of the stories is level 4, which covers the grammar expressions explained down below.
potential form, imperative, passive, volitional, ～とき, から, たら・ば・なら, ～そう, ～よう, compound verbs
causative, causative passiv, ～そう, ～らしい, ～はず, ～もの, ～ようにする・なる, ことにする・なる