Way I see it. Nowadays the twists in manga series follow like these few. Cute girl (MC-2) is involved deep in the game. Muscle-heads die depending on their muscle level: thugs die early, smart bruisers live longer - the former is more common. All pervert characters will almost certainly die, unless they're the MC. Gyaru characters can die early if they're unlikeable or die later if they're likeable. Leader types die early if they're a Type-3 (an idealist) or live up to mid-late to late game if they're a Type-2 (a pragmatist), but rarely does the Leader live. Couples rarely live; their plotline is whether they'll betray each other or continue to love each other.
Authors must really struggle when it comes to breaking out of the dichotomy of characterizations. Additionally, this manga may have drawn inspiration from 999, seeing as the main character's number is 9, and we're now down to 9 characters.