*Delurks* Wow, I just had to comment on what an incredible story this is. Can't wait for more. And yes, I too am tempted to peek ahead at the untranslated, but I don't know any Korean, and this story is too good to let it be spoiled with not being able to read the text. ^_-
I do have to say that I suspected the twist at the end of Ch 28 from the start, but my suspicions were artfully deflected early on. ;)
As for people not noticing the changes. I dunno about the doctor (he may be a quack *shrug*), but for people that saw Ji-Hoon every day, the changes may have been too gradual to notice until they were brought to the forefront by something drastic.
There's a saying about boiling frogs. If you place a frog into boiling water, it will immediately jump out. But if you slowly raise the temperature of the water, the frog will remain in the water until it boils to death. (See
this link on the Boiling Frog at Wikipedia for more information about that saying. n.n
The people close to Ji-Hoon were like the boiling frog. Not noticing the gradual changes, or dismissing them as their imagination playing tricks on them.