UNKO Kanji- weird or not?

Never ask your friends to bring you some crazy souvenir from Japan, because THEY WILL. Well short story to be told one day I discovered an article which talked about the #1 kanji book on Amazon JP. It wouldn’t be anything special if it wasn’t for this one thing…  the main character of these rather fantastical series is no other than Mr. Poop. WAIT WHAT?! Yep, in Europe, this would be viewed quite shockingly ( my mom’s ‘ew what is this’ can totally back it up) but in Japan it was trending? and number 1? That is something interesting…. So the me who found out my friend is going to Japan for a trip immediately asked for this book. Although my friend’s reaction was ‘wtf’ at the start but I still discovered the book in the souvenir bag I was given. haha… 

Apparently, it was so popular and got quite a lot of positive feedback. In total there are 6 books out there. 

What do you think about this interesting way for kids to learn with this character?