The main characters are likely to be the ones from the original 'world ends with you' game, such as Neku Sakuraba.
In the 'world ends with you story', Neku Sakuraba is the main protagonist. He's a complex character who has to grow and change throughout the story. Shiki Misaki is an important female character. She has her own dreams and desires which play into the story. Joshua Kiryu is a character full of intrigue. His actions and motives are not always clear at first. These three characters are at the heart of the story, with other supporting characters coming in to help build the world and the plot as Neku tries to survive in the UG.
The main character is Neku Sakuraba. Shiki Misaki is also a very important character. There are also the Reapers like Joshua who play significant roles in the story.
The 'world ends with you extra story' often involves further adventures in the unique and stylized world of the game. It might include new character developments, additional challenges, and deeper exploration of the game's themes.
In 'neo the world ends with you story', Neku is a very prominent character. He is the kind of character that the audience can easily root for as he evolves. Rindo is another key character. He is faced with many difficult decisions and his actions play a big role in how the story progresses. Fret also has an important part. He is more of an upbeat character, and his positive attitude sometimes clashes with the more brooding nature of other characters, which adds an interesting layer to the story. And there are other characters too, all of whom are intertwined in the complex web of the story's plot.
I'm not 100% sure, but probably Neku Sakuraba is one of the main characters. He's often central to the story in the 'The World Ends with You' series.
In 'The World Ends with You full story', Neku is the protagonist, a teen with a lot of emotional baggage. Shiki is an important character; she has her own motives and personality. She helps Neku open up. Beat is a brash and energetic character. He adds a lot of action and humor to the story. There are also the Reapers, who are antagonists in a way but also have their own backstories and reasons for their actions in the game world.
I'm not sure as the name doesn't give away the characters directly. But it could be lovers who are trying to figure out their relationship using the love equations.
The protagonist is one of the main characters. And there are various Servants like Saber, Archer etc. Each Servant has their own distinct personality and abilities that play important roles in the story.
Not having read it, I can only guess. There might be a protagonist among the regular passengers who has to deal with the extra passenger. There could also be a character who is initially hostile to the extra passenger, and another who is more sympathetic. Maybe there is an authority figure like a conductor or a ship captain if it's a story set in a vehicle or on a ship.
Since it's an extra story related to Soma, it's likely to feature the main protagonists from the original game. They might be joined by new characters as well. These new characters could be related to the existing ones in some way, like being from the same organization or having a common goal. However, without more information, it's hard to say exactly who the main characters are. It could also be that some minor characters from the main game get more spotlight in the extra story and become main characters in this new narrative.