The player is apparently programmed to load data based on the harem json files requested from the server when you play the harem scene, but that apparently doesn't apply to the story, apparently they load the assets in directly (or at least some, I've seen a couple of jpg and mp3 files in the network feed). Technically that means you can indeed make a player for the main scenes.
However, this player doesn't do that, so either you're gonna have to code the program yourself to include main scenes, or somehow figure out how to download all the assets and compile them into a format the player can read and accept. Good luck with so much trouble, I'd rather just use the browser