Tao-sheng Commentary on the Lotus Sutra, p168There were also the eight dragon-kings
All these dragon kings are named Joy. They were (once) reincarnated in human form and resided in Rājagṛha. When suffering from drought, the king and ministers went to them to seek help. Immediately the sweet rain fell and the rain soaked the whole country. Seeing the rain fall, the people were very pleased; hence, the name joy.