In Nuki Doki-, players take on the role of a high school student who has been transported to a mystical realm where angels and demons coexist. The story revolves around the protagonist's quest to create and manage a team of characters, each with their unique abilities and attributes, to compete in a series of battles against rival teams. As the protagonist navigates this new world, they must build relationships with a cast of colorful characters, including angels, demons, and other supernatural beings.