I'm not sure specifically as it depends on the particular visual novel. But it could be a young man and a young woman, with the man perhaps being a bit of a misfit and the woman having her own set of quirks.
I'm not entirely sure without more research, but usually in a high school romance story, there would be a male and female lead. They might be the typical high school student archetypes like the shy girl and the somewhat clueless guy.
Since it's a teenage romantic comedy, there could be a group of friends as main characters. There might be the nerdy but kind - hearted guy, the popular and confident girl, and their friends who are all involved in each other's romantic escapades. Maybe there's a best friend who is always giving bad advice, which leads to more snafus in the relationships.
The main characters include Hachiman Hikigaya, a cynical and introverted high school student. Yukino Yukinoshita, a beautiful and intelligent girl who seems cold at first but has her own insecurities. And Yui Yuigahama, a friendly and somewhat naive girl. These three characters form the core of the story's relationships and character - driven plot.