Tsukune Aono might also be a key character. In the original Rosario Vampire, he has his own story and in fanfiction with Shirou, they could be friends or rivals. Inner Moka, the more powerful and assertive side of Moka, would also be an interesting addition to the cast of main characters in the fanfiction.
Obviously, Shirou is a main character. And in the Rosario Vampire setting, Moka Akashiya is likely to be an important character in the fanfiction as well. She is a vampire and her interactions with Shirou can create interesting storylines.
One good story could be 'Shirou's Adventure in the Rosario Vampire World'. It might show Shirou using his skills in a unique way within the Rosario Vampire universe. Another could be 'Shirou and the Vampires', which could focus on his relationships with the vampire characters.
Kurumu Kurono is a succubus. She is in love with Tsukune and often gets jealous when Tsukune shows interest in other girls. She uses her succubus powers to try and win Tsukune's heart at times.
Tsukune is central as he is the character around whom the harem forms. Moka is often a key figure in the harem, with her alluring vampire nature and the mystery of her two personalities. Kurumu, with her seductive succubus powers, also adds a lot of drama and romantic tension. Yukari, the young and sometimes mischievous witch, brings in elements of magic and her own brand of charm to the story.
Well, Tsukune is of course one of the main characters. He's the human who gets involved with the supernatural world of the Rosario Vampire universe. Then there are the members of his harem. Moka is a very important character. She's a vampire and has a split personality, which makes for an interesting dynamic in the fanfiction.
The main character is Tsukune Aono. He is a human who attends Yokai Academy. Another important character is Moka Akashiya, a vampire. There is also Kurumu Kurono, a succubus.
The main characters include Tsukune Aono, a human boy, and Moka Akashiya, a vampire.
In the 'Rosario Vampire Long Story', the key characters are Tsukune Aono, a human boy who enters the monster - infested school. Moka Akashiya, a vampire, is central to the story as she has a special relationship with Tsukune. Kurumu Kurono, the succubus, who has feelings for Tsukune and often gets into comical or tense situations with Moka. Yukari Sendo, the witch, also has her own unique abilities and personality, and together they all create a rich and diverse cast that drives the story forward with their interactions, conflicts, and friendships.
Tsukune Aono is often a central character. As a human in a school full of monsters, his reactions and growth throughout the fanfiction are usually interesting. His relationships with the female characters in the harem, like Moka Akashiya, are key elements of many stories.
One idea could be Shirou finding himself in the Rosario Vampire world and having to adapt to its unique rules. Maybe he uses his skills from his own world to protect the school from various threats that are different from what he's used to.
Shirou's projection magic could be really interesting in the Rosario Vampire world. He could project weapons that are effective against the various supernatural beings there. For example, if there are werewolves, he could project a silver - edged sword.