Wow, this twist would be more refreshing to the already tired basic formula of the Conan chapters. And let's add school sub-plots with other girls at school wanting to befriend her, the occasional boy who is attracted to her and all of that added to crime stories and solving cases.

Something like Christie not wanting to socialize with girls of her new age, but a girl wants to become her friend anyway, an attack by the association occurs and the detective ends up saving her by inadvertently becoming her friend. As the days go by, she ends up making friends with a rich and pedantic girl to solve a case, but once it's over, Christie now has to put up with that pompous girl, but with the benefit that she will later invite them to luxurious and extravagant places, either on vacation or some exclusive event. And how about a hyperactive and observant girl who has a keen attention to detail? What if she accidentally helps Christie in a very delicate case and when solving it this happy girl but very attached to her friends sticks to her like gum? Even if she doesn't want it, Christie now has friends who want to do things for girls her age, play, go for walks and talk about certain things, like that mysterious handsome boy from the next class who doesn't stop watching Christie. The detective confronts him, only to realize that the boy is just shy and that she wants to confess that she likes him, which leaves Christie gaping and her friends excited. At least she already has someone to give chocolates to on white day. Let's not even talk about another more assertive and athletic child who seeks Christie's attention. Despite his age, he is very brave, once standing up for the detective against thugs armed only with a pipe, so he practices kendo in his family's dojo. They barely made it out alive and the boy received a severe beating but he did not cry or be intimidated, because his grandfather taught him that this is the path of a man. This sparked in Christie a strong sense of admiration for his strong confidence and manhood, though, sometimes she blushes whenever she thinks of him too much, so that display sparked something else.

Uff. This gives a lot of juice. And that only improvised a couple of things.

holy cow, you really have story potential with this going on ^^

Professor Agasa is surprised that a little girl is Shinichi Kudo. But she managed to convince the Professor that she is him. After her first case, the Professor gave Christie all sorts of gadgets, a voice changing bowtie, tranquilizer watch, and sneakers which a single kick makes a harmless item the force of a cannonball.

Hattori couldn't believe that a little girl was the Detective of the East. He was taken aback at first but agreed to keep her secret. Soon both Detectives are partners though Hattori couldn't help but point at the fact that she couldn't have all the luxuries of a boy now that he's a girl. This kind of infuriated Christie as football and Ran are his two favorite things.

Soon Christie would meet a young boy named Manato Haibara, the creator of the poison that turned her into a kid and a girl. Manato is currently in hiding from the Black Organization who is hunting him. On the plus side, Manato admitted that it would be harder for them to match the resemblance because of the poison's effects.

Not sure why I am a stickler for alternate universe having to have the near same storyline.