I endorse this manga... as one who just wants to sleep between a pair of oversized mammaries.
@hoboshoe : Your comment did catch my attention... and you're right... mostly. Different species generally can't produce viable offspring... can't... or won't. There is precedent for the distinction drawn between species to be behavioural, or even just a matter of being far enough apart that they don't encounter each other. The incompatibility doesn't need to be physiological.
Two lifeforms that COULD produce viable offspring but are too far apart, active at mutually exclusive times of day, or simply don't regard each other as candidates for mating... can also count as different species.
@Scynix : You mentioned a bear one? What bear one? I'm curious. I've somehow read two manga so far where a guy fucked a bear... and somehow I don't think either of them were what you're talking about as neither was specifically about bears. Now I think about it, if there is a third manga where a guy fucks a bear, Japan has a lot to answer for.