Who are the main characters in 'testament light novel'?

One of the main characters is Basara Toujou. He is often at the center of the story's events and has his own set of abilities and challenges to face.

I don't know for sure, but it's likely there are Shinigami characters as the title implies.

Maria Naruse is also among the main characters. She plays an important role in the group dynamics. Her personality and abilities contribute to the overall story development. For example, she often helps Basara and Mio in their adventures and in dealing with various threats.

The maou is likely one of the main characters. However, without having read it in great detail, there are probably other important characters like the maou's allies or servants who play significant roles in the story.

The main character is the new sister devil, of course. And there are likely to be some other significant characters around her. Maybe there's a mentor - like figure who helps her understand her powers and her place in the devilish world. There could also be an antagonist, perhaps another powerful being who opposes her for some reason, like power envy or a difference in ideology.

The main character is a male protagonist who is thrust into this world of devils and magic. There's his devil sister, who plays a crucial role in the story. There are also likely other female characters who form part of the harem - like setup, each with their own unique traits and backstories that contribute to the overall plot as they interact with the main character.

The protagonist is an important character. He often has to navigate through the complex world of the novel.

I'm not entirely sure without reading it thoroughly, but likely there is a Maou character as the title implies.

Well, there's Basara, of course. He's the one around whom the story revolves as he tries to handle his new family situation with two sisters. Mio is a major character being a demon lord candidate. She has a certain charm and power that attracts different characters. Maria, with her own unique personality and abilities, is also one of the main characters. Additionally, characters like Zest, a succubus who gets involved with Basara and the others, also contribute to the story's development.

I'm not entirely sure as I haven't read it fully. But typically in such light novels, there would be a main character who is likely to be the shinmai maou or someone closely related to that concept.