C class is about average strength for most demons. They're stronger than the E and D classes, but their power pales in comparison to B class demons and above. These demons are very common and are relatively abundant in both Human and Demon World though more abundant in the demon world as Spirit world keeps a close watch on any demons that are C class or higher.
From what is seen from the series, C-class is the first class to consist of extremely human-like demons, not resulting from a loss of power or transformation, whose only unusual features are different colored hair (or skin) and the occasional non-human feature such as pointed ears or horns. Personality-wise, there is wide variety, there are some that are arrogant and sadistic, but smart enough to not overestimate their strength; or eccentric ones like Chu and Jin who are carefree and optimistic. In short, C-class is the equivalent of normal humans, each with their own personality and views on life, but still have an interest in battle and retain instincts to guide them, while they rely more complex strategy to defeat enemies, rather than the threats of E-class and physical power of D-class. In terms of power, a C class demon can move at supersonic speeds, survive contact with lava, lift several tons and easily destroy large boulders. Aside from power, what further sets C class apart from D and E class is the fact that C class demons have a level of mastery over their demon energy. They can use energy based attacks and manifest specialized abilities that the D and E class demons are incapable of. Most C-class in the series have either risen to A-class and above, or have died due to their overconfidence. A single C class demon can destroy a small town or kill a small army of soldiers without serious trouble.
- The majority of characters in the series are, or have been, C class demons.
- During the Chapter Black arc, Sensui tells Yusuke's group that the demons that were the first to arrive at the tunnel to Human World were C class, despite describing them as mindless beasts only thinking of hunger. Even some A Class demons believe this to be true. The demons are either actually D Class causing a continuity error, or that due to the series' continuing darker plots, the demons were in their purest nature, not influenced to civilized thought by Spirit World or Human World.
- It can be implied that the greater wisdom and insight gained by C class demons comes from the discipline and control gained from mastering their demon energy. This would allow them to control their instincts more and give them a better sense of their opponents as most demons D class and under have little to no sensitivity regarding the beings they come across and would not be able to tell if their opponents were really weak or just concealing their power.