
Maybe he has trauma so he forgot everything about that time.

I think he had some sort of accident and memory loss was involved. I am sure this story isn't too picky about the science of it, but there are brain injuries that can make it impossible for people too recognized faces--even of your spouse and kinds. Maybe this is something like that. He remembers that he used to enjoy high school, but he can't recall the people.

Yeah, I've also thought of a brain injury or a certain kind of amnesia, but I 'read' the raws (well, I looked at the pictures ^^") up to chapter 26 and it doesn't seem like it (yet). So maybe he's always been a shallow guy who just doesn't care about anyone but himself? Or maybe I misread the raws. I'm just saying, if his memory loss can't be traced back to a brain injury or the like, then it doesn't seem plausible to me...

It's very subtle, but in the first chapter, it mentions that he had an accident when he was a courier.
http://iweb6.mangapicgallery.com/imgfiles/warehouse/1/033.png
The artist rarely draws in facial features--I wasn't sure if that's her style or if that is representative of Dohyon's mind. Much of the story seems to jump the way Dohyon might think or experience/remember bits of things.In the first chapter, he also seem both quick tempered and impulsive, which can happen after injury (but this is fiction, so....)
What I don't understand... how is it possible he can't remember the names and faces of his former friends? I can even remember the full names and faces of all my classmates from primary school (even if they weren't my friends) and it's been 20 years since then o.o
If he was a playboy back then, okay, maybe he can't remember all of his affairs, but his friends? ~.~