At the end in the bonus pages, is the implication that Takahiko and Licht are also having sex or is Natsuko just messing with Terumi's (Gretel) head or is it just a throwaway joke that I'm reading into too much? Hmm..
@Alokrhea1 Natsuko wrote and sold an erotic fiction novel starring Takahiko and Licht... using their real names and family relation, presumably without permission. Daughter finds out, gets pissed, then Natsuko teases her about how she used to find trashy novels of exactly that sort hidden at the back of her bookshelf. Natsuko elaborates that she got the idea due to how Licht was always following Takahiko around like a second shadow. That's all it is.