Guy dies, turns into a monster called a behemoth (which apparently starts looking like a house cat), and finds horny elf who wants to breed with cats. He takes down a dragon, and with its death, it prays for the ability to breed with a strong man like the little kitten that murdered it, and the dragon gets a human form in order to be a monster cat fucker too (which would be the related image). As a behemoth, he can learn other monster abilities, so he does have interspecies breedability for whenever his harem of girls thirsty for cat finally get their way.