(2023) ИЗУЧЕНИЕ ЯЗЫКОВ | ЯЗЫКИ ВОСТОКА | ЯПОНСКИЙ III/455

Languages Study | Languages of the East | Japanese III

AUDIO 455 | GRAMMAR II - 22.02 : ... nasai, shinasai

verb stem + なさい (... nasai, shinasai)

The verb stem + なさい - nasai is a command (* 3).
It has a strong implication that you are "talking down" to somebody, or that you are more mature, know better, and should be obeyed. 
なさい, therefore is appropriate for parents to use toward their children or for teachers toward their students.

You also often see nasai in exam instructions.

* 3

nasai goes directly on a verb stem, and therefore it can only be used for commands in the affirmative.
To issue a command in the negative, you can use the te-form + wa ikemasen, which we learned in Lesson 6.