On March 3rd of 2025 of the human realm, a crystal of chaos from outside the Phlogiston which had been falling down the Abyss for many thousands of years cracked.

The crack of such a powerful old one like the crystal sent shock waves throughout the Abyss and went on to shatter the sphere which contained the realm. 

The shock waves flew through the Phlogiston and whaled against the surrounding realms, the Spirit Realm was tilted and its containment sphere shattered also. 

The Human realm neighboring the spirits was too hit, but its sphere only cracked, however the tilting of the spirit realm sent it careening into the humans, the impact between realms shattered the sphere protecting the human realm, causing the two to merge. 

The physicality of the human realm overlapped with the spirituality of the spirit realm, the two became one.