This is a short branching VN with four separate endings. For most of the game, you pick choices for the girls, selecting their route to the demon king and which disasters they'll encounter along the way.
There is not a single scenario where the girls can win. There's only one route where they even get to try to fight to the demon king, and they can't even hurt him.
The final choice at the end of each route is for the demon king, to determine what ending you're getting (21-25+30-34, 81-84+51-55, 77-80+68-76; 26-29+85-87).