DIGIMON
LEGEND OF THE FOUR GUARDIANS

In episode 33 of Digimon Adventure 02 ("Chance Encounter" in the English version), Yolei went to visit Kyoto on a class trip. In this episode, Yolei doesn't just run into the standard digimon, she learns more about the two worlds and the legends surrounding it. Yolei meets up with Joe's oldest brother, Shuu, and Sora's father. They explain to her something quite interesting about Kyoto.

Kyoto is special in many ways. It is said that it is a place where the worlds collide. Therefore, creatures find it easier to pass through to Kyoto than other places. This is also why people built temples in this area.

There is also an explanation on the four guardians. It is said that there are four guardians protecting the city -- Genbu to the North, Suzaku to the South, Byakko to the West, and Seiryuu to the East.

In certain aspects of Chinese mythology, it is said that there are four guardians protecting the land. This is the same legend that is found in Digimon, and in Fushigi Yuugi. (You can read more about its use in Fushigi Yuugi here.)

In Digimon, there are four guardians protecting the Digital World. These guardians are made up of four mega digimon. These guardians are the Digital World's equivalent to the four guardians that are said to protect the real world. They are the equivalent of the four guardians.

In episode 37, "Kyoto Dragon", the digidestined meet up with Azulogmon. Azulogmon is Seiryuu, the dragon guardian of the Eastern Hemisphere of the Digital World. He explains that the four guardians were sealed away. After the Dark Masters were destroyed, the crests of light and hope were able to break Azulogmon's seal.

"That's correct. There are many similarities between your world and ours. After a long battle, we guardians were sealed away by each of the Dark Masters. They didn't even leave us something to read. It was then that seven of the eight digidestined came to the Digital World. And once the seven had returned to their own world, the Dark Masters dismantled it and reshaped it to fit their own needs. The eight children and their digimon were able to defeat the Dark Masters, but we were still trapped beneath the seal. In order to break the seal, we needed to take away the power from the digidestined crests. Of course, Joe complained about it, but he complained about everything. Unfortunately, it meant the digimon could no longer digivolve to their ultimate levels." -Azulogmon, Digimon

Even though not all the four guardians have appeared in Digimon, there are mega Digimon that represent them. Here's a chart to help explain them: