I don't know as I haven't read this graphic novel. But they could be a diverse group of characters like heroes, villains, or ordinary people caught up in extraordinary situations.
I'm not entirely sure who the main characters are specifically as I haven't delved deeply into it. But usually, in a visual novel, there are characters that drive the main plot forward.
Another important character is Rakushun. He is a very likable character who befriends Yoko and helps her understand the ways of the Twelve Kingdoms. His unique perspective as a non - human in this world adds depth to the story, and his relationship with the other main characters is full of heartwarming and also sometimes tense moments.
Maybe there are characters such as a wise old man or woman who imparts knowledge about the twelve days to the younger characters. There could also be a group of friends or family members who are central to the story. For example, a mother and father who are trying to make the twelve days special for their children. And perhaps there's a mysterious stranger who shows up during the twelve days and changes the course of the story.
Youko Nakajima is a key character. She is a normal girl from our world who gets transported to the twelve kingdoms and has to adapt to a whole new life. There are also other important characters like Keiki, who plays an important role in guiding Youko in this new world.
There might also be some supporting characters who play important roles, like the wise old sage who gives guidance to the guardians. He helps them understand their powers better and the significance of their mission. And there could be some antagonists as well, perhaps a powerful dark wizard who wants to disrupt the balance that the guardians are trying to maintain.
Maybe there are some characters like a wise old man who imparts the true meaning of the twelve days of Christmas, and a young child who is experiencing the magic of Christmas for the first time. There could also be a group of friends who gather during the twelve days and have their own adventures and revelations.
The main characters are, of course, the Konoha Twelve. This includes Naruto Uzumaki, Sasuke Uchiha, Sakura Haruno, and others. They are the focus of the fanfic and usually the ones driving the story forward with their actions and decisions.
The main characters are the twelve brothers, their stepmother, and their sister.
Obviously, the main characters are the old bears themselves.
I'm not sure specifically which 1986 graphic novel you're referring to. There are so many graphic novels from that year. Without more information, it's impossible to say who the main characters are.