ない～はない

The construct [X] ない ... [Y]はない is used to mean something like "There is no X which does not/is not Y. It's essentially stating that all X's are Y.

このクラスには、宿題をしない学生はいない。休む時に、先生に連絡しない学生もいない。
In this class, there is no student who doesn't do the homework. And when absent, there is no student who doesn't contact the teacher.

しないおとめはない。
There's no otome that I won't play.

酸素や水を必要としない生物は地球にはいない。
There is no living thing on the earth that does not need oxygen and water.

私のトキという猫に買わないおもちゃはない。
There's no toy that I won't buy for my kitty Toki.