After seeing that Haru seems to be the only one who can change the storyline of Secret, I have started thinking about a theory. I think Haru is literally the Haru from the "Trumped Creeper" comic, and he traveled through those Portals in order to find a comic in which Dan Oh existed. Dan Oh probably died in the "Trumped Creeper" comic and Haru, in his desperate state, went through those Portals in order to find a "world" in which she was alive. But the consequence of traveling through a Portal is that he loses his self-awareness and memories. And since Haru didn't actually exist as an actual character in "Secret", he is able to not be 100% controlled by the writer and change some things inside it.
That may explain why he has that scar to begin with, even though scars normally disappear when the next Stage happens, because he didn't get the scar in "Secret" but on another comic. And it explains the flower that Haru always looks at which symbolizes "waiting", because after traveling through different comics and losing his self-awareness everytime, he has to wait for Dan Oh to find him and "wake him up", waiting and hoping that she can recognize him once again so that they can finally be together.