Kamu is the eldest of the Dukes, and once was a tyrannical king in his own right before the Overlord conquered the world. Kamu's kingdom, whose name nobody dared say aloud (and consequently has been lost to history), was a small but fiercely guarded collection of crags, towers, and mountains that look like crags and towers, all bristling with defensive fortifications. Kamu had a large and extremely untrustworthy family, which he would periodically cull in ever more imaginative ways. Once he held a feast in a hall whose entire floor had been converted to a trap door over the kraken pit; once he held a "lightning catching" contest on the roof during a thunderstorm; once he mailed packages of Nutter Butters to all of his relatives with nut allergies. In short, Kamu spent so much time thinking of ways to slaughter his own family that he was unprepared to resist the Legions of the Overlord when they appeared on the horizon. Kamu's insanely defensive fortifications were enough to convince the Overlord, however, that it would be easier just to make the reclusive king a Duke in the new regime.
Kamu retains a fierce sense of injustice to this day, spending much of his time looking for lost heirs to his throne, so he can kill them in imaginative ways. Kamu always refers to himself in the third person, and Speaks With Lots Of Capitals. It's really annoying, but visitors must be very careful not to roll their eyes, because Kamu is sensitive to that sort of thing and keeps closets full of spiders for such people.