Mystique in the Mirror

Alan is an ordinary young man with memory trouble. His life changes when he begins seeing the ghost of a strange old man every time he looks in the mirror.
Alan's dad thinks what he's seeing are hallucinations and sends him for treatment at a psychiatric hospital. There, Alan meets Darwin, the guy in the room next door, and the two develop a bond. However, no matter what, Alan's doctor isn't able to rid him of his hallucinations. Alan begins to suspect what he's seeing aren't hallucinations; rather, he suspects he's being haunted. If so, it means there's something in the past—something Alan isn't remembering—linking him to the ghost of this old man.
With Darwin's help, Alan begins to look into his own past. The issue is, Alan comes across a document that reveals his father has long since passed away.
(Source: Thai = mebmarket.com || Translation = MDL)
~~ Adapted from the novel "Mystique in the Mirror" (ใครในกระจก) by Patrick III Rangsimant (รังสิมันต์).