Work Text:
So basically I was thinking it would probably start with Conan helping someone, whether with a case or something else, and they are grateful so they they give him the book as a thank you. Then he forgets about it for a little while, and when no one is home he sees it and decides to read it.
He opens it and one way or another accidentally used windy and blows the other card away. Cerberus pops out and tries to explain the situation, but Conan doesn't believe him.
After some convincing Conan tells Cerberus about his de-aging.
The rest of the fic would be about the canon events of Detective Conan/Case Closed along with his trying to secretly catch all the cards.
If some one writes this, go ahead, just give me credit for the original idea. Also let me know if you do somewhere in the comments, I would want to read it.