As we don't know the nature of 'girls side 4th story', the main characters could be very diverse. They could be girls from different backgrounds, cultures, or age groups. It could be a story about a team of girl athletes, in which case the main characters would be the members of the team, their coach, and maybe a rival team's members. Or it could be a story about a girl detective, and the main characters would be her sidekick, the suspects, and the people she helps in the course of solving mysteries.
I don't have enough information to determine the main characters in 'girls side 4th story'. It could be a group of friends who are girls, sisters, or classmates. Maybe there are characters like a young girl who is the protagonist, her best friend, and a mentor figure.
Since it's a side story related to Swing Girls, the main characters are likely to be the girls from the original Swing Girls story. They are probably the ones who are at the center of the new adventures or events in this side story. Maybe there are also some supporting characters like their music teachers or friends who help them in their journey in this side story.
The two main characters are Chito and Yuuri.
I'm not sure specifically as it depends on the actual story. But it could be the same main characters from 'Girls x Battle 2' like the female warriors or leaders in that game world.
It could be a story that focuses on the fourth part of the journey or development of the girls in question. Maybe it involves their growth, relationships, or challenges they face at this stage. It could be a narrative in a book, a game, or a movie series. For example, if it's a series about a group of girls in a school, the 4th story could be about their senior year and all the events that come with it like prom, college applications, and new friendships or rivalries.
Typically, the main characters would be the T - Dolls associated with the UMP Cafe. UMP45 and UMP9 are likely to be among the main characters as they are often associated with UMP - related areas in the Girls Frontline universe.
I'm not sure exactly who the main characters will be in the side story. But it's likely that the main character from the original '19th life' story will play an important role.
In games like this, the main characters often include the protagonist, who is usually the player's avatar or a character that the player can control. Then there are the female characters that the protagonist interacts with. These female characters likely have distinct personalities, like some might be shy, others more outgoing, and their personalities will influence how the relationships develop in the game.
In 'west side side story', Tony is a key character. He is part of the Jets gang. Then there's Maria, a beautiful young woman who is Bernardo's sister. Bernardo is the head of the Sharks gang. And Riff, as the leader of the Jets, plays an important role in fueling the gang rivalry. Their actions and relationships drive the whole story forward.
I'm not able to recall the main characters in the Decameron's 5th day 4th story precisely. However, in the Decameron, characters often include young lovers, wise elders, and cunning servants. It's possible that the 5th day 4th story also features such types of characters, who get involved in complex relationships and situations that drive the plot forward.
Since I haven't studied the 'decameron 5th day 9th story', we can only make some speculations. It may have a male protagonist who is on a quest for something, perhaps love or wealth. There might be a female character who is either an object of his affection or an obstacle in his path. And there could also be other supporting characters like friends or family members who influence the actions and decisions of the main characters.