I know that the original questions is old (and that Ariari is now aiming at the N3 
), but I would recommend taking a look at the なぜ?どうして? series. The theme is "answeing questions kids often wonder about", i.e. why do we yawn? Why doesn`t the spider get stuck in it`s own net? Who was Isaac Newton, etc.
They are aimed at school kids from first to sixth grade, and maybe first grade material corresponds to N4. There is a couple of books for each school year and there is a natural progresseion built in from year to year.
I have read some of them and I plan to recommend them fron now on, everytime something about doing Tadoku comes up on this forum
Here is links for editions aimed at first graders:
http://www.amazon.co.jp/dp/4052031458
http://www.amazon.co.jp/dp/4052034090
http://www.amazon.co.jp/dp/4052039076
), but I would recommend taking a look at the なぜ?どうして? series. The theme is "answeing questions kids often wonder about", i.e. why do we yawn? Why doesn`t the spider get stuck in it`s own net? Who was Isaac Newton, etc.They are aimed at school kids from first to sixth grade, and maybe first grade material corresponds to N4. There is a couple of books for each school year and there is a natural progresseion built in from year to year.
I have read some of them and I plan to recommend them fron now on, everytime something about doing Tadoku comes up on this forum
Here is links for editions aimed at first graders:
http://www.amazon.co.jp/dp/4052031458
http://www.amazon.co.jp/dp/4052034090
http://www.amazon.co.jp/dp/4052039076