The main character could be a girl from a European country. She has always been fascinated by Japanese culture. One night, she has a vivid dream and when she wakes up, she finds herself turned into a Japanese girl. She then embarks on a journey to explore different parts of Japan, from the bustling cities like Tokyo to the peaceful countryside, all while trying to figure out how she can go back to her original self.
Perhaps a nerdy girl who is really into Japanese manga and anime. One day, while reading a particularly magical manga, she is suddenly sucked into the story world and turned into a Japanese girl character from the manga. She uses her knowledge of the manga's plot to try and change the story for the better while adjusting to her new appearance and life.
It could be a shy and introverted teen boy who was always on the outskirts of his social group. When he turns into a girl, he has the opportunity to reinvent himself and become more confident.
A shy and nerdy boy could be the main character. He's always been into books and science. When he is turned into a girl, he has to use his intelligence to figure out what happened and how to get back to his original form, all while dealing with the social changes like fitting in with the girls at school or in his neighborhood.
Maybe it starts with a magic spell gone wrong. A girl, who was an ordinary American, for example, is suddenly turned into a Japanese girl. She is thrust into a world of kimonos, tatami mats, and anime. She starts to embrace her new identity as she meets a group of kind - hearted Japanese girls who introduce her to the joys of Japanese cuisine like sushi and takoyaki, and she also learns about the beautiful art of ikebana (flower arrangement).
The Green Goblin could still be the main villain. He might see the transformed Spiderman as an easier target now that she's a girl, or he could be even more enraged by the change and be more determined to defeat her.
Perhaps the main antagonist could be a dark magic user who was the one responsible for turning Harry into a girl in the first place. Their goal might be to disrupt Harry's life and his role in the fight against the dark forces. This antagonist could continue to create obstacles for Harry as a girl, like trying to prevent him from getting the help he needs to change back or causing trouble for his friends who are trying to support him.
It could be an ordinary girl named Lily. She is just a normal school - going girl until the shrinking incident happens to her.
The main character is, of course, the girl. She could be a young student who is on her way back from school when the rain starts.
Maybe it's an orphan girl, like Emma, who has always felt different and then finds out she has wings which are the key to her true identity. She might be from a lost race of winged people. The story could be about her journey to find her people and her place in the world.
It could be an ordinary person, like a college student. They are just going about their normal day when suddenly, they are turned into a gorilla. This would make for an interesting contrast between their normal life and the chaos that ensues when they become a gorilla.
It could be the person who finds the doll - dragon. Maybe a young adventurer who is curious about the strange doll.