Supreme Time Demon God

The protagonist is a creature that looks just like a little mutt. Everyone who meets him says he's using cheats, but he always insists he's only doing it to save his younger brother. What they find even harder to accept is that the little dog can cultivate just by eating, and even break through to a new realm while sleeping. That's all because the dog was born with a brainstem System, and a genetic System mutation fused with it, triggering a direct return to its ancestral form. As a result, one mutt chases a certain Divine Emperor until he doesn't dare go home for three days; another mutt defeats every opponent in the universe; and yet another swallows the Eternal Demon Emperor whole...