Japanese Dragons, like most Asian dragons, symbolise water deities and are associated to rainfall and bodies of water.
Chinese dragons, Nagas of India and of Southeastern Asia, etc. There are innumerable examples of stories and legends that intertwine Chinese, Japanese and Indian mythologies.
One thing is common though, the connection to the water element is always present.
Water symbolise emotions too. Dragons may symbolise the flow of our deepest longings and desires. They might represent parts of us that we might want to keep secret because of fear of being rejected.
Dragons are also associated with Fire. Dragons can be dangerous creatures, they produce fear, respect. They will act instinctively and intuitively, and they might burn everything down before they stop to analyse what has disappeared.
I believe there is a dragon inside all of us. I also believe we can learn a lot from them if we listen closely. But if we lock them up and try to stop their true nature from advancing in their own cycles and paths, they will make themselves noticed through Water (emotions), or Fire (rage, anger or instinctual destruction).
Balance of elements. Water. Fire. Air. Earth. Ether. That is the only secret. Giving space for all of them to coexist.
Art: Dragon by Hokusai.