The ニャンニャン探偵団 on the absolute beginners book club!
There are also the 十分読める. These are the easiest actual books that I could find. But to me this only became actually readable after I was done with all n5 and n4 grammar. And by readable I mean that I still have to look stuff up but at least is mostly just vocabulary.
Or you could do something like Read Real Japanese they do a side by side translation of the text with explanations. But this one is recommended to Intermediate learners.
I don’t know how far you are into your studies, but a graded reader might suit your purposes better. They use limited grammar/vocab and increase the complexity of the text at each level. That way you won’t be flooded you with 50-100 new things to learn in a single text.
When you can read a lvl 3 graded reader with no problem, then you could move on to those first two books.