Lensai is a realm that is connected to Earth and is accecible by magic gates.
Thousands of years ago, people from Earth and Lensai lived together peacefully. Over time, the bond between Humans and the beings of Lensai grew farther apart. The people of Lensai took this as if the humans did not depend on the link anymore, and decided that it was time to slowly cut off their resources.
The first thing the ancient Lensai Guardians did was to cut off the magic that they supplied Earth with. They made it so that humans had no access to magic anymore, no matter how they tried. The humans were taking the Lensai for granted, and they were sick of it.
Over time the Lensai people became more independent, shutting off the connection almost completely. The magic barriers and passageways were rewritten to exclude human ability to walk through it. For at least three generations, any form of passage spells were banned, and only Guardians were allowed through, on urgent business.
During these three generations, the humans slowly forgot about the Lensai, the newer generation that came from people who knew of Lensai were skeptical of its existence. The bond that once existed between the Lensai and Humans was reduced to mere fairytales.
When some of the older Guardians retired and were replaced, the ban was lifted. However, new laws were put into place. The laws in place were that all people of Lensei should disguise as a human being and not show their true form on Earth. The Guardians enforced this law as well as they could. This law was in strict monitoring for at least ten generations, maybe more. The exact numbers were never recorded.
The Lensei residents slowly became more cunning over this period of time, finding new ways of disguising themselves. Some gained the knowledge of switching into both human and animal form. Even though that disguising was mandatory on Earth, the Lensai Guardians saw it as becoming an issue. For the last five generations of the law, anyone who used transformation or illusionary magic in front of a human was able to be punished by death.
Once again, as the Guardians switched, finally a sensible Lensai resident was put into power. They made the laws less strict, and allowed all of the races in Lensai, access to Earth passageways. They gave the Angels the power to monitor the gates, to help the weaker Lensai back to Lensai in case of an emergency.
Currently, the Lensai are less hostile towards humans than before, however many humans either don’t know of the existence of Lensai , believe it is just fairytales, or religious practices.