I happened to be putting together an unarmed rager, which was very similar, with one or two differences... I would think that a level of martial artist monk (so no lawful requirement) would work for this character, you would trade a level of barbarian, of cores but you gain a whole lot,
Specifically,
You get the free monk feat (combat reflexes or dodge)
the monk version of improved unarmed strike
"A monk's attacks may be with fist, elbows, knees, and feet. This means that a monk may make unarmed strikes with his hands full. There is no such thing as an off-hand attack for a monk striking unarmed. A monk may thus apply his full Strength bonus on damage rolls for all his unarmed strikes."
This is better than the basic feat for three reasons, one it's far more clear that you can use this to knee/kick/elbow while still claw/claw/biting if your dm is hesitant to allow it. Two it's full strength damage on all unarmed attacks without double slice. Three since it's specifically not an off-hand attack, you also get the normal power attack damage boost
You also get stunning fist (which comes in useful in a bit), plus better saves.
You do lose a point of bab, as well as a rage power and up to 4 hps, and you're a level off for all barbarian rage powers, which means you'll either be a point behind, or even with where they would be normally
You now don't need to spend feats on unarmed strike, or double slice, and then you can't take two weapon rend.
But with those feats saved and having stunning fist, it lets you add dragon style (mainly useful for the charge-pounce) and more importantly dragon ferocity. Now you're adding 1.5 str damage on all 7 or 8 unarmed strikes, with crits automatically giving them the shaken condition for gravy.
Plus you've still got a feat free
As a side note, the tengu is a good alternative to a human for this setup... you don't need the free rage cycle as much as a normal barb, because you don't have as many feats free, and while you lose the feat and the stats aren't as nice, you have the same awesome favored class superstition bonus + 3 natural primary attacks at level 1