You're dreaming now, and so is the rabbit, and you are in the rabbit's dream.
The whole letter isn't long, but this sentence is the only one that carries any substance.
He is dreaming, the rabbit too, and he is in the rabbit's dream.
So, is this underground mall he's in now actually part of the rabbit's dream?
Looking at the information in the newspaper, this underground mall isn't even supposed to exist. Construction had just begun when it attracted the Rabbitman. Therefore, this mall should be fake.
Yu Liang pinched his hand, and he felt the pain clearly. He then pounded at the wall beside him, which was as solid as it seemed.
Is this really a dream?
A dream that feels this real?
Is he dreaming within the rabbit's dream?
This seems to follow the logic of inception.
Looking at the other sentences, it seems that these letters were written by the same person. However, the feeling he gets from each letter is entirely different.