Not having played this visual novel, it's difficult to name the exact main characters. But if we assume it follows common visual novel tropes, there could be a group of characters around the 'aku no onna'. There might be a childhood friend who has a different view of her compared to others, and perhaps a mysterious figure who holds some secrets related to her origin or true nature. These characters would interact with her and drive the plot forward.
I'm not sure specifically as I haven't played it in detail. But generally, a visual novel often involves a story with characters, plot development, and probably some kind of relationship exploration. 'Aku no onna' might be centered around a female character who could be associated with some sort of 'aku' which might mean 'evil' or 'dark' in Japanese, so perhaps it's about her story in a dark or complex situation.
I'm not entirely sure as I haven't specifically played it. But generally, a visual novel often has a story with characters and different plotlines. It might involve themes related to the title, perhaps about female characters ('onna kanbu') in some sort of context, which could be related to a dark or 'aku no' (evil or bad) situation. However, without more information, it's hard to be more precise.
Since I don't have direct experience with it, it's difficult to say for sure. However, some visual novels have unique art styles that set them apart. Maybe 'aku no onna kanbu visual novel' has a distinct art style that enhances the mood of the 'aku no' (dark) theme and the portrayal of the female characters ('onna kanbu').
It could be someone from the Naruto universe who doesn't like Naruto's newfound fascination with Aku. For example, Danzo might see Naruto's interest in Aku as a threat to the stability of the village and try to stop Naruto from further exploring Aku - related things. So, Danzo could be the main antagonist in this case.
The main characters are likely the 'denpa onna' and the'seishun otoko' as the title suggests.
Aku could be a storyteller. Maybe it's a person's name.
I'm not entirely sure as I haven't experienced this visual novel specifically. But generally, a visual novel often has a story line involving characters. Maybe it's about female warriors with some unique characteristics, like in many visual novels where there are adventures, relationships, and challenges that the characters face.
I have no idea whether it is popular or not. It seems like a rather specific and perhaps not so mainstream title. There may be a small niche audience for it if it exists, but without more information on its distribution, reviews, or community following, it's impossible to determine its popularity.
I'm not sure as I haven't played it. But perhaps it has unique art styles to depict the female warriors.
I'm not sure who Aku specifically is. Aku could be a person with a great imagination who tells all kinds of stories, like adventure stories, fairy tales or even true - life stories.