First, decide on the personality and looks of your girlfriend character. Then, think of interesting situations and dialogues they could have. Also, pay attention to the art style - make it visually appealing.
I'm not entirely sure specifically what 'oni uta visual novel' is about without more context. It could potentially be a visual novel related to oni (which often refers to demons or ogres in Japanese culture) and perhaps involve a story, characters, and interactions within that theme.
The exact origin of when oni first appeared in stories is hard to pinpoint precisely. But they have been a part of folklore and myths for centuries in various cultures.
The way to pause a girlfriend comic varies. If it's an online version, there's usually a pause option displayed. For a physical copy, you could either lay it aside or use a paperclip or something similar to mark the page.
Veronica was indeed Archie's girlfriend in many instances within the comic. However, the comic often presented complex relationship dynamics, and there were also times when they weren't a couple. It all added to the interesting plotlines.
Since it's a visual novel related to oni, it could have unique features such as a special combat system if there are battles with oni in the story. Also, the cultural elements of Japanese oni might be presented in a unique way. For example, the use of traditional Japanese music or sound effects to enhance the oni - related atmosphere. The dialogue might also be unique, with the oni having their own way of speaking, perhaps more rough or archaic - sounding. And the story structure could be centered around the characteristics of oni, like their love for chaos or their hierarchical society if that's part of the plot.