Review of Redo of Healer
The idea which Redo of a Healer most attempts to explore is not revenge or whether people are redeemable or not, but rather the idea that one's environment makes a person. The core premise of the series is that a kind/selfless kid was absolutely destroyed by his environment and turned into more or less a psychopathic monster. The story isn't questioning whether Keyaru can be "redeemed" or not, nor whether Flare/Blade/Norn/etc could possibly be "redeemed", but rather examining how their environments changed them and how different environments could make a difference. Flare ended up the way she did because her father is a sociopath who nevershowed her any love, and throughout her childhood she was aggressively scorned by all those around her until eventually she became a Hero and thus got the upper hand on them. She had been hurt by people in positions of power for her whole life, and now it was her turn. Is she "redeemable"? Does the tragedy behind the way she grew up "justify" what she does? Healer as a story doesn't care about these questions. All it cares about is that Flare wasn't born this way - her environment shaped her, and when given a new environment by Keyaru, she changes in turn. It's important to note that although he does lock away her memories, her "nature" still shines through as Freiya, so it's not like he creates an entirely new identity for her. He observes that without her father's racist influence, she never ends up squashing her secret hope for all races (demons/humans/demihumans/etc) to join together and live in peace.
Now, all this doesn't translate directly into Keyaru trying to "redeem" everyone, nor does the series imply he should. That people are molded by their environment is just a fact of reality which sometimes has negative consequences; it's not something that frees people of responsibility for their actions, nor is it something that obligates Keyaru to try to create a perfect environment for everyone (no more so than you or I are obligated to). In the first place, to posit that a character needs to be "redeemed" or not relies on deeming them as inherently evil or inherently flawed, and this is not a judgment Healer attempts to make.
Reason being, it's pretty shallow to try to delineate people between between the archetypes of "good" and "evil", since this is ultimately just playing with language and arbitrarily marking some behaviors as "good" and others as "evil". It's the classic example of how stealing is bad when you do it frivolously but justifiable when you do it to help your family or survive; if you try to think about ethics in this black and white way then you end up spending millennia playing with language without solving any real problems, just like moral philosophers have been doing for quite some time. There's never any end to it and all conclusions are just labyrinth amalgams of senseless words rather than any meaningful analysis as to the nature of human beings.
Naturally, Redo of a Healer is far too mature of a story to be bogged down by such amateurish pitfalls. It's interested in looking at people, how they grow, how their environments shape them (as mentioned), and what they can do to change themselves (e.g. change their environment). These are practical discussions that actually are meaningful, as opposed to being arbitrary ethical constructs. Keyaru is not some shallow moral philosopher wanna-be defining whether people are evil or redeemable or not. He just looks at what they do, how it impacts him, and makes real-life decisions based on those factors. The whole point of the early story, even, is that Keyaruga only kills people who hurt him personally, hence all that stuff about philosophy of revenge (which admittedly is pretty dumb, but the point of all that is that he's deranged anyway).
Point being, it would be pretty infantile to approach Healer as a work of good/evil, redemption/corruption, etc. The characters are nuanced and grow like real humans do. They make their decisions based on their goals and interests. There are no battles of "good vs evil" here (fuck, even the Demon King is explicitly not a bad person). The only morally obsessed character in the series in Kureha and she gets exploited for it, rather than hailed a paragon of virtue.
One we have this established we can finally attempt to judge the show Redo of a Healer on more than a surface level. Discard from your mind all preconceptions of what you think the show is about based on surface-level evaluations: Is it about glorifying the satisfaction of revenge? Is it a simple power fantasy meant to titillate and nothing more? Is it about the author creating evil characters and reveling in creating a Hero that can give them what they deserve? No. At the end of the day, attempting to tie stories down to overarching themes and morals like this is a plague of post-modernisms that infects modern criticism. Redo of a Healer is a quintessential example of a story written with a pure heart, with the author hoping nothing more than to create a world and realistic characters behaving in understandable ways, without imposing any judgment on his own characters or attempting to exploit their struggles to push some theme. J. R. R. Tolkein once said that readers often mistook applicability of allegory, and to understand Healer we must understand the author is attempting to create a world with secondary belief here, not a thinly veiled allegory for real life.
Thus it would be most efficient to analyze Healer by starting with the protagonist, Keyaru. This character is far more profound than the average anime viewer seems to understand, as I hinted at earlier. I think that shallow media out there has given us the implicit understanding that insane characters are actually profoundly intelligent and rational on the inside - the Jokers of the world with their calculated plans and metaphor-laden speeches. Keyaru, however, is deranged. The four years of torture legitimately damaged his mind and deeply hurt his psyche to the point he felt forced to escape into an alternate identity, Keyaruga, for fear of continuing to be his "weak" self, since being himself led to his aforementioned torture. The psychosis and insanity he experiences is all too real, and everyone mocking his actions as stupid, irrational, self-centered, etc are missing the point - that's exactly what a mentally deranged person would do! They wouldn't have perfect rationale for all their actions. They wouldn't have iron-tight philosophies. They would be deranged, and Keyaru is very deranged indeed. Imagine, if you will, how you might imagine an innocent young 14 would react after four years of non-stop abuse and torture. I think it's not hard to imagine them having their mind shatter and being forced to clinging to shallow ideas of "revenge" just to keep themselves going.
Because indeed, he was morphed by his environment, and it was a bad environment indeed. I think people want the author to lambast Keyaru for being so fucked up. Other people want the story to double down and embrace his actions. However, both options involve judgments that aren't fair to make, and the author understands this. The work offers no judgment on Keyaru - it does not call him evil, much like it doesn't call the other characters evil, and it doesn't double-down on justifying his deranged behavior, either. For better or worse he is the product of his environment, and the author is not about to lambast a man for being shaped by his environment. With this in mind we can piece together how the other characters in the story parallel this - Flare, in the way I mentioned earlier; Norn, who did everything she could to earn attention after being ignored for so long, including adopting sadistic and cruel philosophers to prosper in the corrupted kingdom; Bullet, who experienced an unexplained tragedy 3 years prior to the start of the story so terrible that it is shocking that he even can speak or act human at all; Blade, who was raised in luxury and never experienced being chastised for her actions, etc. Are any of these characters determined to be evil? Irredeemable? Redeemable? No. They are simply human beings shaped by their environment, and the author does not choose to make any claims as to whether people hurt or misled by their environment are good nor evil, redeemable nor redeemable, etc. They are simply people, and their behavior in the story reflects this.
Thus begins Keyaruga's rampage. On a technical level, the story itself is a bit unremarkable. Standard fantasy tropes with stats, level caps, and basic adventure with a regular helping of sex to spice things up. However, I think it's far more competent than it's given credit for. Keyaruga's Heal is overpowered for sure, but in general it's most useful for practical applications like making tools/potions/disguises/etc, with the actual battling being best left to the superior fighters such as Kureha. This leads to numerous intriguing scenarios where Keyaruga wins through wits rather than brawn, although the flashy action scenes are definitely more memorable than the alternatives. It's also hard to deny that the revenge scenes aren't highly memorable and entertaining, despite being morally detestable, and being so memorable is truly an accomplishment. But revenge aside, Keyaruga adventuring with his harem is heartwarming and a positive environment for everyone, and despite the brainwashing and whatnot making things a bit more morally complex, the environment truly is positive.
Which ties this into the whole concept of "environments shaping the people". All things considered, Keyaruga's adventuring party is a positive environment for all those involved. It brings out the best in Freiya, Setsuna, Kureha, and Eve. It's a messy and complex situation for sure, but they all end up better people at the end of the adventure, including Keyaruga himself, who slowly find his heart healed as he spends his nights with those who love him. Are the characters good or evil? Are their actions good or evil? Are they redeemable or irredeemable? As I have said countless times, Healer cares not for these immature questions. It espouses a philosophy far more advanced and meaningful - that people are simply people, and attempting to apply grand ethical judgments to the things they do is spinning circles in a game of language. All talk about Healer being morally detestable, or Keyaru being evil, or anything like that is simply missing the point.
Healer is about environments and growth. It's about finding a reason to live and learning to trust other people. It's about life.
Read the LNs if you can. The story slows down a bit in Volumes 4-5 (with the anime ending on Volume 3), but it really goes places by the end, and the depth of the author's ideas become far more apparent when you can peer closer into Keyaru's deranged mind and see the torment tearing him apart.