ENIGMA:

The world is plagued by a mysterious disease known as “Enigma”.

Chester, infected with the disease, ends up on the lonely island of Carlisle.

When the girl who nursed him gives him a tour of the island, Chester senses that something is wrong. There are no doctors from the mainland on the island. Not only is there no information about the outside world, but the inhabitants seem completely oblivious to the worldwide epidemic.

—It’s as if the place has been completely cut off from the rest of the world.

After some time, Chester finds a white forest standing out in the middle of the green expanse.