Since I haven't read or played this particular visual novel, it's difficult to say exactly who the main characters are. However, based on the title, one can assume that there is a character who has a devil in their arms. This could be the protagonist, and perhaps there is another character who is the devil. There may also be side characters such as those from the protagonist's normal life who get affected by this strange relationship with the devil.
It could be about a relationship with a devil - like character. Maybe it involves a story where the main character has some sort of encounter or bond with a devil that ends up in their arms, perhaps in a romantic, dangerous or mysterious context.
Since I don't know the story, I can't tell you the main characters. But usually, in a story, main characters play important roles in driving the plot forward.
I don't know specifically as I haven't read it. But likely there is the 'little devil' character as one of the main ones. There could also be characters who are friends or foes of the little devil, like a normal human who stumbles upon the little devil's world.
Satan is one of the main characters. He is a devil who has been transported to the human world and has to work part - time jobs to survive.
Given the title 'honey x devil visual novel', it's likely that the two main characters are those representing 'honey' and 'devil'. The 'honey' character could be a symbol of all that is good in the story's world, while the 'devil' character represents the challenges or the darker side. They could be two different species, like an angel - like being for 'honey' and a literal devil for the 'devil' character. Or it could be more of a metaphorical representation of two opposing personality types within a more normal - looking cast of characters.
I don't know for sure as I haven't read it. But likely, there is a character who has some sort of encounter with the devil. So, one main character is probably the one who is spending the ten days with the devil, and of course, the devil itself is a main character.
Since it's based on a diary, the main character is probably the diary's author. There might also be secondary characters such as a best friend who plays an important role in the author's life, or a love interest that is often written about in the diary. However, without more information about the 'my diary visual novel', it's hard to say for certain.
Since I don't know the details of 'my master visual novel', it's hard to determine the exact main characters. However, in a visual novel with such a title, you can expect a main character who embodies the role of the master. This character may be joined by characters with different personalities and motives. For instance, there could be a wise advisor character, a strong - willed companion, or an antagonist who opposes the master's plans. These characters would interact with the master and drive the story forward through their relationships and conflicts.
I'm not sure exactly, but probably the 'lady' in the title is one of the main characters. There might also be a male lead if it has a romance aspect.
Since I don't know the specific 'My Girlfriend Visual Novel', I can't say for sure. But likely the main characters are the protagonist and his girlfriend.