The main character could also be a gender - bent Ochaco Uraraka. Imagine her with her cute and charming personality but in a female - dominated hero world, being courted by different male characters. Her gravity - controlling quirk would also make her a powerful and interesting character in this setup.
Another possibility is a gender - bent All Might. As a female, she could be a mentor figure to the younger female heroes. And in the harem aspect, she could have a group of male admirers who are also heroes or trainees. Her backstory as a once - powerful but now weakened hero could add a lot of depth to the fanfiction.
It could be Deku's son or daughter. They would inherit some of his amazing quirk, but also face the pressure of living up to their father's legacy. They would have to carve their own path in the hero world.
The main characters could include Eri. She has a very interesting quirk and her own story of recovery. At the daycare, she could be like a big sister to the other kids. Todoroki could also be a main character. His dual - quirk nature would be fascinating for the kids to learn about. And of course, Aizawa could be a daycare supervisor. His no - nonsense attitude would keep the daycare in order, and his erasure quirk could be used in case any of the kids' quirks get out of hand.
One option is a cat named Whiskers. Whiskers has the unique quirk of being able to create illusions. It teams up with a cat named Paws, who has a super - speed quirk. Another main character could be a cat named Mittens. Mittens has a quirk that gives it the power to control water. These three cats could be the central figures in the My Hero Academia cats fanfiction. They might start out as regular cats but then discover their quirks and decide to use them for good in a world full of both cat and human heroes and villains.
Perhaps in this genderbend harem fanfic, the female Deku is a new transfer student to a school dominated by male students who are all attracted to her kind - hearted and heroic nature. And they all compete to be her sidekick in battles.
One theme is the adaptation of the original story's power dynamics. In a genderbend harem fanfiction of Boku no Hero Academia, the powers might be used in different ways depending on the new gender of the characters. Also, friendship and rivalry often play a role. The characters in the harem may be friends who also compete for the affection of the main character, or they could be rivals who gradually develop feelings for each other.
Ochaco Uraraka is a common character in the harem. Her kind and friendly nature makes her a likely candidate. Momo Yaoyorozu is also often included. Her intelligence and elegance add an interesting dynamic to the harem. And Tsuyu Asui could be part of it too, with her unique personality.
Midoriya could be an interesting pairing. Their relationship in the original series is full of rivalry and mutual respect. In the genderbend version, this could develop into a romantic relationship with a lot of emotional depth, as they both understand each other's journey to become heroes.
Obviously, Naruto would be the central character. But in the genderbend version, characters like Sasuke, Sakura, Hinata, etc. would be genderbent. Sasuke as a female could bring a whole new dynamic to the story. She might be more of a femme fatale type, still having her strong will and desire for revenge but with a different charm. Sakura as a male could be the big - hearted but sometimes clumsy character, always trying to prove himself to Naruto. Hinata as a male could be more shy and reserved, yet still having a deep - seated love for Naruto.
The main characters could also be students who are not related to the current heroes but are inspired by them. They could come from different backgrounds, like a student from a family of villains who wants to break free and become a hero. Or a character who has a very weak quirk but has an unwavering determination to prove that they can be a great hero, just like their idols from the previous generation.
Izuku Midoriya could be a main character. His determination and growth throughout the series would make him a great fit for facing kaiju. He could use his One for All quirk in creative ways to fight the huge monsters, perhaps by focusing the power into a single, super - strong punch that can knock a kaiju off its feet.