Kumonryu means “nine-tattooed dragon,” a name borrowed from a character in Chinese literature famous for the dragon tattoos covering his body. It's a fitting name for a koi whose black, marbled pattern winds across a white base like ink poured into water. What makes Kumonryu genuinely unusual, and part of why keepers get attached to them, is that the pattern isn't fixed. It shifts with water temperature, season, and even the fish's stress level, so a Kumonryu that's almost entirely black in the winter can turn mostly white by summer, then shift again the following year.
Kumonryu is a Doitsu variety by default, meaning it typically has the reduced, mirror-style scaling associated with German carp lineage rather than the full scale coverage seen on most Nishikigoi. That scaleless or partially scaled skin is part of what makes the shifting black pattern so visible and dramatic against the white background.
The variety is relatively young by koi standards, developed in Niigata in the 1980s by breeders working with black Karasugoi and Doitsu bloodlines to fix a pattern that would keep changing rather than settle into a permanent shape. That instability, which would be considered a flaw in a variety like Kohaku, is the entire point of a Kumonryu. No two years look the same, and no two fish develop identically, which is exactly why long-time keepers often say a Kumonryu is the koi that keeps them checking the pond every morning.
Because the pattern is unpredictable, judging Kumonryu at shows comes down to contrast, boldness of the black markings, and overall balance rather than matching a fixed template. For hobbyists, that unpredictability is the draw. A Kumonryu isn't a fish you buy for how it looks today. It's a fish you keep to see what it looks like next year.