Waterhorse Dragons received their name due to their horse-like physique and endearing behavior. They are capable of surviving out of water, and when on land their skin secretes a gelatinous goo to retain moisture. However, their large paddle feet are better suited for swimming, and waterhorse dragons tend to move very awkwardly when on land. Waterhorses are very friendly dragons and enjoy playing with humans.

Dragons are highly-intelligent reptilian creatures that—from a human perspective, at least—appear to live forever. Many different varieties of dragon exist, each with their own unique qualities, habitats, and behavior. Adolescence in dragons is usually marked by the growth of a hatchling’s wings, although not all breeds of dragons grow wings and some breeds have other traits that indicate the beginning of maturation. In Galsreim, dragons and humans coexist peacefully.

His name means "Water Gate" in Japanese. He is the son of Akio and Sazanami. He is a very playful dragon and loves to splash the others when they come to drink. He is not a very fast swimmer, due to a gimp in his right rear leg. When he was still an egg, a giant water snake snuck into his nest and tried to eat him while his mother was away. His mother came back in time, but the snake still managed to bite the egg. Suimon's parents tried their best to patch the egg up, but when he was hatched, his leg was still injured. His injury doesn't keep him from living life to the fullest, and he is incredibly happy. He is even happier since he became mates with Miwaku, and their large families were united. He loves her, and enjoys bringing her beautiful shells from the bottom of the lake, and anything else that he can find that he thinks would be suitable for his beautiful mate. They love each other, and look forward to spending their long lives together, forever.