My guess is that the story got axed the chapter before introducing the "four heroines", and then the story was just rushed to a terrible close afterwards. Essentially this story is horrible, although the concept of calling it horrible is unfair, it's worse than that. I don't think I only speak for mysel when I say, that wihout the fan service parts, I'd've never read this, and if that's all a story has, then that's a rather weak showing.