Without having read it, it's hard to say for sure. However, it's possible that the main characters could include a soldier who is stationed near the gate and gets caught up in the events of the gaiden. There might be a local from the world on the other side of the gate who becomes a guide for the characters from our world. And perhaps there's a researcher type of character who is studying the gate and its properties in this side - story light novel.
Well, 'gate gaiden light novel' could potentially be about all sorts of things. Maybe it's about the adventures that happen on the other side of a mysterious gate. It could focus on the backstories of characters who are involved in the main 'gate' story. Since it's a light novel, it might also have elements of fantasy, like magic or strange creatures that are encountered through this gate in the side - story it tells.
Violet Evergarden is the central figure. Additionally, characters like Cattleya Baudelaire might be prominent. Since she is associated with Violet in the overall 'Violet Evergarden' world, she could have a role in the gaiden. Also, any new characters introduced specifically in the gaiden to further the plot or provide new perspectives on Violet's story could also be among the main characters.
The Goblin Slayer himself is likely to be one of the main characters. There might also be some of his comrades or fellow adventurers.
Since I don't know the specific 'light gate novel', I can't tell who the main characters are.
Yoji Itami is a main character. He is a soldier who gets involved in the events related to the gate. His character is interesting as he has to adapt to the new and strange situations in the fantasy world.
I'm not entirely sure, but it's likely to feature characters related to the sword aspect in the 'Danmachi' world. Maybe there are sword - wielding heroes or characters who have a special connection to sword - making.
I'm not entirely sure as I haven't fully read it, but usually in such novels there is a protagonist who is at the center of the story. Maybe there's also a mentor - like figure who guides the protagonist on his journey.
I don't have enough information to determine the main characters. They could be a young adventurer, a powerful wizard, or a brave knight.
I'm not entirely sure as there could be a variety of main characters. But often in such stories, there would be soldiers from the SDF. Maybe a young and brave officer who takes the lead in exploring the world beyond the gate.
The protagonist is Shin. He's a strong character who has to deal with the challenges of the new world.