Am I the only one not liking this "working under the bad guy" arc? Like, it's so lame that he can just kill Justus covertly and end everything but for some reason doesn't, at least make it so Harold is free like previously mang
Been a long while since I read the Web Novel translation, but I think MC is incapable of harming Justus because of being restricted in some way.
I mean, MC was charged for being a traitor, so it's not easy for him to act without info.
Plus, since he had played the game (or was it a novel he read?), he knows to a certain degree that Justus has multiple plans to counter any scenario, which is why killing him isn't the option (as apparently in the game, Justus is supposedly defeated a lot of times by the protagonist, but he still comes back powered-up the next time).
And since Justus was the final boss, most of his background activities remain unknown to the protagonist aka., the player.