Some were saying that Light's insanity was influenced by the use of the Death Note, taking note that Ryuk tells Light about what the Death Note makes people fear and so on. But having rewatched the first episode, Light tells Ryuk that creating a utopia with the Death Note needs to be done even if it costs you your sanity, so it occurred to me that this was the cause for Light's insanity over the series and not the Death Note, since his main madness is about winning and not about the Death Note.

Then again, in the manga Light's behavior is a little different than in the anime, when Light fears in his bed and mentions his nightmares (and I don't remember Light saying the above in the manga) while in the anime such behavior is not mentioned at all, so it might even be some difference between the anime and the manga.

Anyway, the question is: what influences Light's insanity, the Death Note or his godly craziness, and does this differ between the anime and manga?

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    I've only read the manga, but my reading was always that Light was arrogant and thought he knew what was best for everyone even before he got the Death Note, and the Death Note just gave him a tool to start imposing his ideals on other people. He does hide under the covers but I always read that more as him realizing that it wasn't an academic exercise anymore, and overcoming that due to his arrogant belief in his own righteousness. Later on he definitely also starts to take pleasure in beating others in intellectual contests.
    – Torisuda
    Apr 2, 2020 at 1:00
  • This is kind of what I said - "so it occurred to me that this was the cause for Light's insanity over the series and not the Death Note, since his main madness is about winning and not about the Death Note." it is true to say that Light wasn't like that before but to say that the DN made him that is kind of far.
    – USerNAme
    Apr 6, 2020 at 20:39
  • Yeah, I agree with you that his personality is the root of things. We see from other parts of the manga that you can own a Death Note for a while without murdering willy-nilly; L, Mello, and Near all have them for periods of time. I think his arrogance is the key thing that puts him down this path. It takes a fantastic amount of arrogance to be 18 years old and be so sure you know how the world should be run that you think any amount of death is justified, which Light does from very early in the manga. His later mania for beating L is also arrogance.
    – Torisuda
    Apr 9, 2020 at 0:05

2 Answers 2


I've only read the manga, but from what I remember, the relationship between Light's craziness and the Death Note is complicated. The Death Note facilitates a lot of the steps he takes on the road to craziness, but things could have played out very differently if not for elements of Light's personality that we either see very early or can infer from what we know about his past. (Spoilers ahead, by the way.)

At the beginning of the series, Light is in his late teens, has grown up comfortably in a middle class modern Japanese family, and has been a popular, handsome, academically gifted student his entire life. People have been telling Light his whole life how wonderful and smart he is. This upbringing could easily make a person think very highly of themselves. And it could also easily make a person look down on others who aren't as smart or handsome as they are.

The Death Note drops into his lap, and after getting over his initial disbelief, Light comes up with an idea. He plots out a whole plan to change the world by killing criminals with the Death Note, eventually using the fear he creates to discourage all crime, and even merely unpleasant behaviors. For anyone to believe they know how the entire world should be organized is arrogant. For an eighteen-year-old who's never experienced anything but comfortable living and people telling him how smart and handsome and wonderful he is, it's the most ridiculous heights of arrogance. But Light barely questions himself. He does get scared and hide under his covers in one scene, but he's just committed his first murder and found out the Death Note is real, so there's a lot going on there. He ultimately does decide to enact his plan.

He starts using the Death Note to enact his plan, catching L's attention. He fights to stay ahead of L, and later Near and Mello, using every resource available to him. He takes obvious pleasure in winning and in manipulating other people, such as Misa and the police on the task force. He becomes more and more sure that he knows how the world should be run, and takes steps to solidify his control. When he finally does lose in the end, he doesn't go down gracefully. He screams, blames his allies, hurls insults, and tries to kill one last person with the scrap of Death Note hidden in his watch before being shot by Matsuda and then finally killed off by Ryuk.

There was definitely something in Light's personality that made him think his will should be imposed on the world. There was definitely an arrogance that made him think he was morally superior enough to start killing people to achieve his goals. But without the Death Note, he would never have had the tools to do what he did. So in that sense, the Death Note made him a murderer; with the tool for easy, consequence-free murder in front of him, he went right ahead and used it. The way he thinks about what he's doing seems to shift as things go on. Murder becomes less and less of an issue for him, and he shifts from murdering only criminals to murdering just about anyone who gets in his way, including his own father. And that too probably wouldn't have happened without the Death Note. The Death Note made murdering easy, convenient, and consequence-free (or so he thought, since he believed he could outwit anyone who came after him). He already looked down on other people. In his most charitable moments he thought of them as poor benighted fools who needed his protection. Usually he thought of them more as either pawns he could manipulate or roadblocks to be destroyed, and he shifts more and more to that way of thinking as the series goes on. So as he commits more and more murders, the idea of committing one more, of killing one more disposable inferior human, barely registers as a concern. So he kept murdering, and got in too deep.

But at the moment L started coming after him, Light could have decided it wasn't worth the risk and stopped using the Death Note. He didn't, because his arrogance would never allow him to admit defeat. When L pulls the trick with Lind L. Tailor and gets Light to kill his double on a global TV broadcast, Light doesn't get spooked and back down and sink into obscurity. He ramps up, declaring war on L, and that spirals out into everything else that happens after that point. So his personality, his arrogance, pushed him into the situation where he had to kill more and more people to stay ahead. That's all on Light; the Death Note didn't make him do it.

  • I will add only this - what you said is even showed in Light and L tennis game, Light didn't even dare wants to lose but either to lose to not being showed as a winner, in other words - not to lose, and that didn't even was about killing and stuff.
    – USerNAme
    May 11, 2020 at 22:34
  • That's a good point about the tennis game. It definitely does show Light's arrogance and how much he hates losing anything. He never seems to consider that he might actually lose honestly and not throw the game as part of some scheme, and he considers throwing the game because it might mean winning some larger game L is playing with him to uncover his identity.
    – Torisuda
    May 14, 2020 at 21:17
  • Now that I think about it, it may seem in the anime better the manga in the first ep - Light is translating eng to jap in the class and get bored since there's no competition, he sure want to be top in the class to be the "winner" even to be bored with it. I say in the anime since I don't remember it in the manga. (this may seemed speculated but it fits to your answer)
    – USerNAme
    May 15, 2020 at 0:00

I think it is just Light in his pure essence, what I mean is that he is like that, but the power of having the Death Note motivates him to show his darkest side, no more limits or fear.

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    That's actually what I thought I put in my question, but it is still doesn't answer - is there a proof or evidence for that? because I can give a lot of theories myself.
    – USerNAme
    Apr 6, 2020 at 20:37

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