it’s just Kitty Detectives, no Hello Kitty involved 
But yes, I would highly recommend it as a first book! It’s very likely we’ll be reading the dog versions next year, so if you see わんわん探偵団 why not pick those up too 
As a next step up from those I’d highly recommend 銭天堂, which we also read as a book club. It’s a series of childrens books and it was very readable and entertaining. Then I’d probably work up to something like 時をかける少女 as suggested by Dwarsen.
That’s all assuming you’re looking for recommendations from a learning perspective though. In terms of just ‘good books’… I haven’t read enough to say 
but you could look at what the Intermediate Book Club has enjoyed. I would recommend the manga ARIA though (the collector’s edition is beautiful).