To someone new to the series, it might seem implausible that the Main Character has so many uses for his healing abilities. But according to Word of God, the reason why is because the author had previously put some thought into how healing would work on a pseudo-scientific level. Quoting a random commenter who went in-depth on how Keyaru's powers worked specifically, it's thus:
Normal healing is basically remodeling organic matter to match a past state. For this, the healer gets all the data of the person he's healing, which is what causes him great pain. Then, that raw data is compiled & narrowed down to the state the injured parts of the person we're healing will be restored to, and the healer can start the healing process. This basically means that the healer has:
All the data on everyone he touched in raw form (he tends to lose it quickly because he can't remember that much information with accuracy).
The power to get new data.
The power to change the structure of organic lifeforms, especially humans.
Yet this downplays the uses of the other's users magic, with Fire Magic being limited to just hurl fireballs, while in reality is about the creation of pure, raw thermodynamic energy, and control it: It could be used to power structures, machinery, weapons, or de-power someone's body (I.E. take the energy from the heart, or the brain) As many other series have shown us before, with a lot of imagination and good planing, ANY POWER can be a GameBreaker. Yet only Keyaruga uses his power beyond the basic.
Keyaru notes that Proum had easily visited the Demon King's castle when in the previous timeline it took years for the Heroes to even track it down. The Demon King when the Heroes finally tracked the castle down was that timeline's version of Eve, but when Proum visited it was still Hakuou - who is an accomplice of Proum, who in the previous timeline could easily redirect the Heroes as it pleased him. In the previous timeline Proum did just that until Eve killed him and became the new Demon King, at which point Proum not only stopped interfering but sent Norn to help them do the job faster.
While she had her memories erased, Freia/Flare still feared Norn when her name was dropped: does that mean that there is still a sliver of the original princess somewhere in her mind that is desperately trying to break out? Worse, does that mean that not only is the original person still in there, does that also mean they are completely helpless and forced to watch what Keyaru did to their bodies?
Given more credence in the light novel and manga, as Norn’s original personality and identity are explicitly implied to be gradually breaking through the “Ellen” persona, though the long term results of this, and her awareness of events since she became “Ellen”, are not yet clear...
As the story lays out clearly in later chapters, both Flare and Norn used to be happy, cheerful children who had a positive and doting sisterly relationship with each other. But when Flare gained her Hero Crest, King Proum, their own father, began to threaten Flare, forcing her to mistreat and demean her beloved younger sister as now being the “inferior” child. This, amongst other abuses by Proum, caused Norn’s personality to change into her sadistic, evil, power-hungry, twisted, strategic-genius self. This change in turn terrified Flare so much that she developed further into the alpha-bitch persona she carries early in the series, including her tendency to abuse servants as a form of “affection” - something she was taught to do directly by Norn herself. The resulting escalating spiral of fear and villainy resulted in Flare and Norn as we now know them. As a result, every terrible act caused by the two princesses of Jorial (including every bit of suffering enacted on Keyaru throughout the story) can be laid squarely at the hands of their abusive father and his complete lack of affection for the daughters he manipulated into weapons of pain and suffering.
Due to the fact that it is said in the web novel that Keyaru's Heel–Face Brainwashing only erases the memory while retaining the victim's personality, why would Norn before being Driven to Villainy have thoughts of incest.
As mentioned in the YMMV page, Keyaru using rape as a war tactic can be eyebrow-raising and/or seen as contrived given that he was a victim of it for years...unless you can take it to be a very twisted example of Promiscuity After Rape.
Alternative Title(s):Kaifuku Jutsushi No Yarinaoshi
