{{Lore}}
Kappa are one of the a number of [[youkai]] species. At first glance, they appear to be short humanoids with colorful skin, partially resembling [[toadpeople]]. However, they possess many distinctive traits. Their skin color is usually on the spectrum between blue, green, and yellow, and is notable for not having any [[human]] color tones at all. On very rare occasions (less than 1% of the population), certain individuals are born with completely matte black skin; such individuals are simply referred to as ''black kappa'' ('''黒河童''', ''kuro-kappa''). Because of this, kappa consider the color black to be lucky.
On most parts of their body, kappa skin has a scaly texture, resembling that of a [[giant tortoise|tortoise]]. These scales are larger and harder on their backs than it is on the rest of their body, which further reinforces their turtle-like appearance. Most kappa have very colorful hair as well, the most common colors being shades of blue and green. Kappa also possess pointed teeth, capable of tearing through flesh with ease, and with which they deliver capable of delivering the occasional nasty bite. Although large bodies of water are very rare in the Mazes, they are perhaps the only sapient species that is capable of swimming and remaining underwater for any significant periods of time.
Kappa are among the shortest species of youkai, with an average height of just 4 feet 7 inches. Their constitution is usually very slim, bordering on lithe, with a very low average weight of just 90 pounds for both males and females.
If kappa could only be described using one word, it would be their ingenuity. Kappa have a near-supernatural understanding of physics, mechanics and machinery, and are practically natural-born engineers. It is therefore no surprise that the vast majority of youkai engineers belong to this species. Besides the various fields of engineering, kappa are also known for being competent weaponsmiths, with certain [[Muramasa|legendary]] [[Ryuukiri|weapons]] in the Mazes being kappa-made creations.
Though they may be short and seem unsuited for combat, their intelligence and their natural affinity for technology more than compensates for any natural weaknesses they may possess. As a common saying goes, it is very unwise to underestimate a kappa.