Starless_Eclipse
Unless he needs to eat all of a creature to gain there power which is a bit illogical he could just eat parts of her and let her regenerate I’m sure she’d be willing so long an he explains his power due to her feeling indebted to him. If you don’t want him to have it because it’s to overpowered and would stop him ageing and most of his future struggles you could just make it like a unique skill from tensura. (so long as she has the skill he can not) Also just found this story and read all of it, I hope you continue it was an enjoyable read. (Also just thinking will the teacher do something irrational changing some of the original story, and I hope she joins the harem she is adorable and due to that world being medieval she won’t be getting married easily because in that sort of time everyone marry young so you could argue the mc would be doing her a favour)
TF Dude, you are taking Ayakashi to be Chaotic Evil or Chaotic Neutral person while he is actually a Chaotic Neutral to True Neutral, and Yue also isn't a mindless robot or someone who will be happy with everything her significant other does, she prefers romantic stuff seeing she was angry when Hajime took the logical step when fighting the Alraune.