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.
Complete Monster: Dr. Kenmi was revealed as this in later episodes. To activate the mysterious Darkstone powers, Kenmi enacted torturous experiments on people and had murdered one heroine, Rinoa's, parents in order to force Rinoa's sister Aoi to activate her powers. Kenmi later attempts to rip out another heroine's heart after causing her financial ruin for his experiments, and is even revealed to have been behind the 'random' Darkstone attacks early in the series that had caused so much grief, all in an attempt to force his test subjects to go berserk.
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.