These are what we call the 'YMMV items.' Things that some people find in this work. We call them 'your mileage might vary' because not everyone sees these things in the same way. This starts discussions in the trope lists, a thing we don't want. Please use the discussion page if you'd like to discuss any of these items.
He secretly performed experiments on those with the Sacred Seven powers, ultimately dooming them to eventually becoming complete Darkstones.
In episode 7, it's revealed that has been using Fei's Darkstone brother, Hung, as an attack dog.
In episode 10, it's revealed that he was the one responsible for the deaths of Ruri's parents, the crystallization of her twin sister Aoi, and the death of Makoto's Battle Butler dad five years ago.
Then in episode 11, he kidnaps Ruri herself, intent on cutting out her heart and taking her Sacred power for himself. When that fails, he brutally finishes Hung for good and promptly absorbs his power instead.
He also reveals that he was behind all of the "random" Darkstone attacks in the series in a bid to unleash Alma's power, endangering countless innocent lives in the process.
Magnificent Bastard: Kenmi in how he keeps himself out of suspicion even with evidence looking right into the protagonists faces.
Moral Event Horizon: Kenmi crosses it if not for his inhuman experiments, its for his murder of Ruri's parents and the crystalization of Aoi to get her to activate her powers. On Christmas no less.
Narm: In episode 12, Fei turns into a Darkstone as she thinks Naito has died because of her uselessness. The fact that she wants to kill Kenmi is very dramatic. The fact that her Darkstone armor resembles a purple and green robot bear with ears that would make Mickey Mouse's jaw drop completely ruins the drama.