No necrocommenting, but Keansor's comment made me want to talk in the pointless commen section (lul).
Nice job pointing out that plot hole. Bruh. The MCs clearly japanese and you're not gonna interrogate his origins? Is he a player? Is he from a novelized version of the real world? Although the group was sent away, doesn't seem like she put up much of a fight in trying to go back and meet the hero.
The Hero getting ganked disappearing is, well, that makes sense IMO. The demon lord said himself his only "fears" are the goddess and Lufasa. Why he went to meet the hero in the first place then. IDK. Maybe because he thought Lufasa was going to see the hero? Should've been explained then. That's where that plot hole is IMO.
The chapter largely implies that Diina is, in fact, the goddess. With the gesture implying to "keep quiet" as she says the only one who could weaken Lufasa, is the goddess herself. Considering the fact that she was the one who brought Player Lufasa into that world in the first place, it shouldn't be surprising that she is aware of "player" existences and can thus, pose as one.