As I don't know which 'another anime novel' it is, I can't tell you the main characters.
Since there's no specific information about this 'another anime novel', it's impossible to determine the main characters. It could be a group of young heroes on a quest, or a single protagonist dealing with personal and external challenges in an anime - like world.
I'm not entirely sure as I haven't fully explored all the details of Anime Another Sub Story, but usually there would be a protagonist who drives the story forward. There might also be a sidekick character who supports the main character.
Since I don't have detailed knowledge of this novel, it's hard to say exactly. However, based on the title, the central character is surely the 'girl'. There could be other supporting characters like a love interest, a mentor - type figure who helps her understand her place in this 'different planet' situation, or antagonists who oppose her unique way of being.
It could be that there is a male lead who is on a quest of some sort. Maybe he is trying to uncover a secret related to the events of 2001 in the story. And there might be a female character who is his ally or love interest, helping him along the way.
I don't have enough information to say who the main characters are. It could be anyone from an ordinary person trying to figure out their alternate lives to a more fantastical character like a time - traveler or a reincarnated soul.
I don't know as I haven't read it. It could be a young protagonist trying to find their place in this 'another life' situation.
The main character is Yuu Otosaka. He has the power to possess others briefly. There's also Nao Tomori, a girl who is part of the organization dealing with those who have special abilities. Ayumi Otosaka is Yuu's sister.
The two main characters are Yasuri Shichika and Togame. Shichika is a unique swordsman from an isolated island. He has a very different fighting style compared to traditional swordsmen as he doesn't use a sword in the beginning. Togame is a smart and determined strategist. She is the one who initiates the quest to collect the twelve swords and recruits Shichika to help her.
Momonga is one of the main characters. He's the protagonist who gets trapped in the game world.
Perhaps there is a group of friends. One of them might be the central character who is given this second chance, and the others play important roles in either helping or hindering this new opportunity. For example, one friend could be really supportive, while another might be jealous and try to undermine the main character's efforts.
The protagonist is a young man who suddenly finds himself in another world with his smartphone. Along his journey, he meets various characters. There are likely some friendly locals who help him understand the new world. There may also be antagonists, like those who oppose his presence or have different goals that conflict with his. But the exact details of these characters would depend on how far you are into the novel.