I don't know as I haven't read it. Maybe the title implies there is a character experiencing their first day in heaven, but without reading it, it's hard to say who the main characters are.
Since I'm not acquainted with this light novel, I'm unable to determine the main characters. It would be great if there were some details available like a short excerpt or some reviews that could give a hint about the characters. Maybe there is a character who is not having the expected experience in heaven, but that's all we can guess without proper knowledge of the story.
I'm sorry, I haven't read this light novel so I can't give a summary.
The main character is Xiao Yan. He is a determined and talented young man on his journey of growth and power - seeking in the story.
I'm not entirely sure as I haven't read the 'Principles of Heaven Light Novel' in detail. But typically in a light novel, there would be a protagonist who drives the story forward. There might also be a sidekick or a group of friends who support the main character in their adventures.
Dio is surely one of the main characters as the title implies. There might also be characters like Jotaro Kujo who often has conflicts with Dio in the JoJo's universe. They could be involved in battles and power struggles in this light novel.
The protagonist is surely one of the main characters. He is the one driving the story forward with his quest for the heaven - defying sword. Then there's his mentor, who plays a crucial role in his early development and provides him with important knowledge and guidance.
I'm not sure exactly as I haven't read it fully. But usually in such light novels, there is a central protagonist who drives the story forward.
Well, from what I recall, there are the everyday people in the town who are the recipients of the phone calls from heaven. There could be a lead character among them, perhaps someone who is more vocal about their experience or more determined to find out the truth behind the calls. And then there are likely to be supporting characters such as friends and family of those receiving the calls, who are also affected by this strange occurrence.
I'm not entirely sure as I haven't read it in a while, but there are likely characters who receive the phone calls and those around them.
A possible interpretation is that the 'first day in heaven painting' is about new beginnings. Just as a new day on earth is filled with hope, the first day in heaven is the start of an eternal and blissful existence. It could show the main character in the painting being introduced to the wonders of heaven, like the music of the spheres or the knowledge that is available there.
Since I haven't read this particular 'first awakening light novel', I can only guess. It might have a typical hero - type main character who experiences the first awakening. There could also be a mentor figure, someone who has already gone through a similar process and can guide the main character. And of course, there may be an antagonist who either fears or wants to use the power of the main character's first awakening for their own evil purposes.