From the Start, I Contract the Campus Belle and Her Mother, Turning Them into Beast Girls

Beast girls + a harem + no female lead + System + a brainless, wish-fulfillment read. If you don't like it, don't read it. This world has been invaded by alien beasts. Killing them can yield crystal stones. Women who take the crystals become beast girls, while men who take them can form contracts with beast girls. Men and women can fight together to repel the invading beasts. Wang Ming was a broke high school senior with no talent, but he unexpectedly obtained the Super God Contract System. Even without crystal stones, he could contract with beast girls, and there was no limit to how many. With the System's help, Wang Ming fought beasts, fought people, and took on powerful elites, climbing to the top step by step, only to discover that the entire world was nothing more than a game.