Numbats! Fat? Ehn. Fluffy? So fluffy. Rodent? No, numbats are marsupials.
So, numbats (Myrmecobius fasciatus). They live in Australia, eat only termites, and are diurnal. Like the aardwolf, they’re quite small, and they lack the strength to just rip the shit out of a termite mound, so (again, like the aardwolf), they’re stuck ripping open the tunnels leading up to the mound and nomming on the termites they find there. Them being diurnal is a function of them not being able to get into mounds proper; they’re stuck foraging when the termites are active if they want to eat.
Unlike the aardwolf, which can lose up to a quarter of its body weight during the termites’ off season, numbats can go torpid during colder months when termites are less active in order to conserve energy. Numbats can’t, however, just switch to eating other invertebrates if termites are scarce, and they definitely can’t switch to eating vertebrates. It’s pretty much termites and the occasional incidentally-eaten ant or nothing, so this is kind of a necessary adaptation.
Numbats don’t have pouches to carry their young around in after their two-week gestation period, so they’re stuck wedging their babies into a sort of pocket formed by swollen belly-glands and puffy fur.
Above: Numbats are weird.