Another important character could be an oracle or a seer. This character might have foreseen the hero's transformation but was not believed. Their presence can add an element of fate and inevitability to the story. Also, there may be a group of followers who were loyal to the hero but then have to decide whether to follow the new demon king or oppose him, which can create interesting internal conflicts within the group.
Well, generally, such a plot often involves a character's fall from grace. Maybe the hero is betrayed or faces some unbearable situation that leads to his transformation into the demon king. It could be a story full of moral dilemmas and complex character development.
The demon king is surely one of the main characters. He must have some unique characteristics, like great power and a complex personality. The hero is another main character. He could be a young and brave individual with some special abilities. And there may be other important characters, for example, a wizard who has some connection to the summoning spell or a princess who the hero is trying to protect in his own world and that affects his actions in the demon king's realm.
In a typical'mightiest leveling system novel', there could be a main character who is the key player in the leveling system. This character might be an underdog at first, like a young orphan or a novice adventurer. There may also be antagonists who are either jealous of the main character's progress in the leveling system or are trying to disrupt the system for their own gain.
It depends. Sometimes the demon king can be portrayed as a hero, depending on the specific plot and character development of the manhwa.
Obviously, the son of the hero king is one of the main characters. There might also be his father, the hero king, who could be present through flashbacks or as an influence on the son. And there may be a mentor figure who helps the son on his journey, perhaps an old knight or a wise wizard.
Obviously, the son of the hero king is a main character. He is likely to be at the center of the story's events.
Without reading the 'the demon king arrives novel', it's difficult to name all the main characters. However, based on the title, the demon king is central. There may be a prophet - like figure who foresaw the demon king's arrival and is trying to gather forces to stop him. And perhaps there are characters from the demon king's own realm who either follow him or betray him during his arrival in the new world.
The main character is surely the selfish demon king. There may also be some characters who oppose him, like brave knights or powerful mages.
There is likely to be the demon king - to - - be as the main character. And probably some supporting characters like his mentors, rivals, or friends.
Since it's a 'demon king retry novel', the demon king is bound to be a central figure. There could also be characters who oppose the demon king, such as brave knights or powerful mages. And perhaps there are some neutral characters who get caught in the middle of the conflict between the demon king and his opponents. For example, ordinary villagers or merchants who are affected by the demon king's actions and the battles that ensue during his retry.