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5 Reasons L Knew Light Was Kira in "Death Note"

Jeremy enjoys anime when not working as a chemist or building manager.

L and Kira

L and Kira

L and Light in "Death Note"

Death Note features protagonist Light Yagami using the titular notebook to supernaturally execute criminals, while the detective known as L leads a team that pursues Light, known to the public as "Kira". The anime features brilliant cat-and-mouse mind games where Light tries to eliminate L (Light's notebook needs a name and face to kill someone) while L hones in on Kira's identity.

In fact, there's actually quite a bit of evidence that L figured out Light pretty early on; L himself tells Light he suspects him as Kira. Yet some of the clues L deduced are pretty subtle and not always highlighted within the series—here are five points L used to determine Light Yagami was Kira!

Light beats L in tennis

Light beats L in tennis

1. Light's Victory in the Tennis Match

Starting off with admittedly our weakest point, L eventually challenges Light to a tennis match. Light considers throwing the match, reasoning that L knows Kira hates losing, but decides against it as something that might just make him look more suspicious—plus, well, Light hates losing.

So, while even L admits a tennis match is far from hard profiling evidence, he's not surprised to see Light aim for victory: "look at that...he's going for the win." It's a subtle yet still tangible clue to Kira's identity.

L reveals himself to Light

L reveals himself to Light

2. Light Fits Kira's Profile

It's easy to forget some of the smaller clues the Task Force uses to began narrowing the pool of suspects throughout the show, and how they really start to point at Light. As early as Episode 2, L proves Kira's existence through Light killing Lind L. Tailor in the live broadcast, and it narrows Kira's location to the Kanto region of Japan.

From there, L discovers Kira has access to police records, suggesting he's a police member or relative, and he learns the timing of the killings fits a student's time schedule. Upon actually meeting Light, he sees how smart Light is and that Light has strong views regarding justice, as well as great pride. In fact, when L very first reveals his identity to Light, Light briefly panicks, and L most likely read that Light's expression went beyond the general surprise someone would have at L revealing himself; Light was more distressed than an innocent would have been.

Light threatens Raye with his fiancée's life

Light threatens Raye with his fiancée's life

3. Light's Comment on Raye Penber

After police information was suspected to have been leaked to Kira (Light had been utilizing his police chief father's computer), FBI agents began investigating police and their relatives. But Light concocts a plan to trick agent Raye Penber into giving up the names of his fellow agents; Light then kills Penber outside a subway.

While Light's hooded appearance and avoidance of cameras shielded him from surveillance, Penber's death actually leads Light into perhaps his biggest vocal slip-up in Episode 10.

Here, L tells Light that Penber acted strangely before dying, suggesting Kira involvement, and that FBI agents had been investigating police. But Light responds "and Raye Penber was investigating me..."). While we don't get to see L's thoughts at this point, he gives Light a knowing look, then compliments Light's deduction powers, presumably in an attempt to keep him talking and hopefully misspeak again.

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It's possible Light could argue he simply deduced from L's context that Penber had been tailing him, but this moment is probably the show's most forgotten clue (as it comes and passes quickly) L utilizes.

Light examines the crime scene photos

Light examines the crime scene photos

4. Light Fails L's Deduction Test

Although Death Note has one of the best English dubs of all time, here's a scene that works better in Japanese; I'll explain why after we summarize it. L presents Light with three photos of messages Kira had prison inmates write before death—Light recognizes these messages, of course, since he orchestrated them. However, the photos have odd print numbers on the back, which, when arranged in print order number, jumble up the message, which Light tells L is odd. However, L reveals there's a fourth (fake) photo, a new message that Light knows is a forgery since he never made an inmate write it.

The reason why this makes Light look so suspicious is clearer in the Japanese edition, as the three original messages, arranged in the print order L utilized, left a hanging sentence: L did you know, Shinigami who eat nothing but apples…

Therefore, someone who wasn't Kira but has great deductive skills would very possibly infer there are additional pictures and ask for them—the fact that Light didn't pick up on this points to him as Kira.

Plus, soon afterwards, L asks Light how Light would, if Light were L, go about proving someone to be Kira, and L notes that Light has a suspiciously fast answer—other detectives L had asked required minutes to formulate one.

L intercepts Light's call to Misa

L intercepts Light's call to Misa

5. Light Contacting Misa

Near the beginning of episode 15, Mr. Yagami asks L how much L suspects Light, and L responds "the truth is, I don't even know what to think anymore." He admits he's starting to feel doubt, partially because Light has begun creating false alibis and partially from stress due to L's own life being at risk.

However, later in the episode, L surprises Light at college, and then Misa, who L already suspects as the second Kira, arrives. Light thinks he's won (as Misa can learn L's name by simply looking at his face), but oddly, L smiles.

This is likely because seeing them together reaffirmed L's belief that Light is Kira. As if that weren't enough, after Misa leaves, Light makes a lame excuse that he needs to use the restroom (he wants to call Misa and get L's name), then attempts to call her, only for L to answer, having pickpocketed her phone. This further assures L of Light's guilt, leading to the incarceration of Light and Misa that Light is only able to end by having the pair forfeit their Death Notes and thus lose related memories.

Why Didn't L Arrest Light?

So, if L was even more confident about Kira's identity than the show let on, why didn't he simply have Light arrested? Well, primarily, he needed more tangible clues that would persuade his colleagues and eventually serve to convict Light; arresting the guilty only proves beneficial if they can be handed a guilty sentence.

L knew he needed to be able to convince first the other members of the task force, then ultimately a judge, before arresting Light would make sense; he knew keeping Light close was dangerous, but also the best chance at getting more evidence about Kira.

Does learning these tidbits about L make you reconsider your opinions? What might you have done differently in his shoes (or, in L's case, lack thereof)? I'd be interested in hearing your comments and look forward to seeing you at our next Death Note review!

© 2022 Jeremy Gill

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