This list of mythical creatures that begin with this letter and I am constantly gathering information from each continent, and is continually being updated.
Zennyo Ryuo (Japanese)
Zennyo Ryuo "goodness-like dragon-king" or "goodness woman dragon-king", respectively) is a rain-god dragon in Japanese mythology. According to Japanese Buddhist tradition, the priest Kukai made Zennyo Ryuo appear in 824 AD during a famous rainmaking contest at the Kyoto Imperial Palace.
The oldest historical record is the 937 CE that states in 778 CE five Buddhist monks went to the mountain and ceremonially prayed for the health of future Emperor Kanmu, who later established the Muro-ji Temple in appreciation. This text also states that in 781 CE, "a Dragon King who had been residing at this site vowed to protect the country and particularly the temple complex.