While I stumbled my way through a previous Wani Kani book club and learned a lot, this is the first manga I can safely say I actually read with the help of the Wani Kani book club. A very nice level of grammar and vocabulary and really cute art and stories.
I still think about the tower of animals to scare the humans and laugh.
If you're debating trying a Wani Kani book club I really recommend starting with this one.
Most detailed tests
The best practice tests of any book I've used by far. For taking the tests, the format is exactly the N5, the audio app works well (rare for many of these books).
But the strength of these practice tests is in grading. Not only do they actually have accurate grading for each of these practice tests in the JLPT unique grading system, the answers are incredibly detailed. In many cases they also review why the wrong answers are wrong which many practice tests don't do. Highly recommended.