I don't know what is worst that I misunderstood the I am only a sister to you (she probably meant he thinks of her as a tool or something) or that I didn't mind the incest route.
uhhhhhhhh
but seriously tho what is up with incest?? Why is it a thing?? Is it really not that hard to just put adopted brother/sister whatever like still creepy but not blood-related creepy... considering this is a trend among isekai artists I rlly think they need to see some therapists. Or read Oedipus and see how that ended.