This paper presents a study based on the planning and development records of a visual novel game utilizing the White Day. Recently, there has been growing demand for anime-style art and narrative-driven games, with visual novels at the center of this trend. These games provide players with control over the progression of the narrative, offering the enjoyment of determining its branches as a core experience. To deliver this experience, the research team developed a visual novel using the White Day IP. Throughout the project, the storytelling structures of visual novels and pre-existing game examples were analyzed to identify the strengths and weaknesses of each structure. The choice system of the game was then modified and applied specifically to the White Day visual novel, designing a unique branching narrative structure. The characters and settings were adapted to fit the context of the IP, with some adjustments made to reflect the flow of time. To enable rapid, story-focused development, a system was created that allows game designers to review narrative branches without programmer assistance. This iterative design process focuses on examining the fundamental enjoyment derived from narrative and storytelling structures. Through this study, the impact of branching story structures on the visual novel experience was explored, providing a reference case for future game design processes related to narrative branching.