Watching the clip again, I caught a particular detail. War Tiger, Blue Dragon, Sun Bird, Shadow Shell, guys these characters are based on the Four Heavenly Beasts of Chinese mythology!:
https://en.wikipedia.org/wiki/Four_Symbols
These four beasts are associated with the four directions, four elements, and a host of other qualities. Furthermore, they are a staple of Japanese anime. Fans of Yu Yu Hakusho will definitely remember the Saint Beasts arc.
The more you know!