Data Ravelさんのイラストまとめ

In the World of Information the Digimon realize that the symbols carved on the Crests are actually the symbols that are in their hearts, that started to shine.

The darkness would be back in Digital World. Darkness is the real enemy, although a physical body must exist, the difference between this new entity and everything they have ever faced must be fundamental, a completely different existence.

Ancient Dino Region inscriptions describe this entity that long ago appeared on the other side of the Wall of Fire located deep within the Digital World. Its distorted space-time, almost destroying the world. Unable to win, the Digimon called the Chosen Children.

Another major focus is on the "existence that caused distortions in the world and the Dark Masters just gained power from those distortions". An "evil possibility" that has been sealed away for a long time and whose existence drives the world into chaos.

The cave of darkness is only reflecting the feelings of darkness that already exists inside Sora's heart, all she needs to do is throw those feelings away to break free. Right now, Sora is in a environment of dark waters just as Yamato was, "drowning" in her feelings.

Yamato's loneliness was what drew darkness to his heart creating this cave. But now that Yamato and Gabumon are together and the loneliness no longer makes sense, the cave of darkness falls apart and they are both free now.

But Yamato realizes that this isn't the case. These were the same pitch-black feelings he had been feeling so far, it was not trying to enter him, but to pull the darkness that already existed inside him, darkness that has existed somewhere deep inside his heart.

As this continues, we have the scenario of an aquatic environment with "dark waters" and Yamato drowning in those waters. A clear representation of how he is feeling at the moment.

As Yamato continues to develop these depressive thoughts, a "gas of darkness" begins to appear and approaches Yamato.

We see this world at work in the anime when Yamato moves away from the group and begins to develop the thought that he was useless and not even his role as Takeru's big brother really was true anymore. He gets lost in those thoughts and falls into a cave of darkness.