Why make the reveal that the dark night is actually the hero in the first chapter? You could just hint at it: say that the hero is missing or dead, make the orcs say that the knight killed the hero and then hint at the fact that he might have run, suggest something about the past of the knight with someone they meet.
I feel like the reveal could have been an entire plot point, maybe an arc in anime terms, but it was just explained as a fact and not a point of conflict. Its not dramatic to know he might have to face her later, because everything points to fluff and wholesomeness. It's not interesting is we are not afraid that might happen. Talk about the hero loyalty to the humans so later when you reveal that they knight was the hero we feel conflicted.
I know not everything has to be a plot twist and I like the manga and i'm still reading, but I fear it falling into the same problem many mangas like this: it's just one idea repeated over and over again, which is fine if you want some fluff, but it could be fluffy and dramatic at the same time. Manga is just so used to be so unoriginal that any one idea can be made into a whole series... sorry this is just rant territory