between the lines; line spacing
行間を読みなさい。
Read between the lines.
行間をあけてください。
Please leave some space between the lines.
行間を読むべきなんだよ。
You have to read between the lines.
作者の真の意志を知るためには行間を読まなければならない。
To understand the author's true intentions, you have to read between the lines.