u/daniphntm

In Light’s case, everyone who had ownership of the Death Note was unhinged and not completely ideal, but they technically “worked” for whatever plan he needed at the time. Light is supposed to be this super genius with incredible deductive reasoning skills, and he gave Mikami a plan where he was supposed to act as Kira because his lord and savior, the one person he looked up to more than anyone, couldn’t move freely.
The plan was for Mikami to send Takada the names of the criminals while it looked like she was carrying out Kira’s judgments. So when Takada was publicly kidnapped, Mikami knew that his God, Kira, had no way to move freely beyond Takada and that if she was captured, she needed to be eliminated.
I feel like Light should have been able to deduce before the Yellow Box meeting that there was a chance Mikami acted on his own. If I was Light, that would’ve been my first thought. I would’ve been asking myself if there was any oversight in my plan because Mikami was the exact type of person to take matters into his own hands if he thought it was protecting Kira. Instead, Light just assumed Mikami followed the plan perfectly without stopping to consider that possibility.

I honestly think the Japanese Task Force played a role in L’s death, not directly, but by constantly resisting him and slowing the investigation when he was actually right from the beginning.
From the start, there was already a major issue: the Task Force had a leak, which is exactly how Kira was getting police information. L correctly narrowed Kira down to a very small profile early on, someone in Japan, a student, and someone connected to police files. That already strongly pointed toward Light Yagami. Even without hard proof, his deductions were extremely accurate and logical.
The problem is that the Task Force constantly didn’t fully trust L, even though they were the ones dealing with the leak in the first place. Instead of fully backing him and taking his conclusions seriously, they kept questioning his methods and acting like he was going too far,especially when he detained Light, who is the police chief’s son.
Then you also have Misa Amane showing up basically out of nowhere, immediately in love with Light, while openly idolizing Kira at the same time. That alone is already extremely suspicious since Light is supposedly working to catch Kira. On top of that, Misa is directly tied to the Second Kira case, including having her fingerprints on the tapes. To L, none of this clears Light, it only strengthens the suspicion. But instead of trusting that logic, the Task Force starts pushing back against L more than they question the suspects.
That’s not even mentioning how many coincidences stack up around Light and Misa together. From an investigative standpoint, it doesn’t make sense how often the Task Force brushed off things that should’ve raised even more suspicion, especially when L had already been correct about so many things.
Even the imprisonment situation shows this. L detains Light and Misa because they are his strongest suspects, but the Task Force starts doubting him and even pushing for their release, acting like L is being unreasonable. Meanwhile, L is still consistently following the only logical lead the case has.
Obviously, L doesn’t die because of the Task Force directly, Rem is the one who kills him. But my point is that their lack of trust, hesitation, and resistance slowed the investigation at key moments and gave Light more time to manipulate everything. If they had fully trusted L’s deductions and followed through on his lead earlier, the case could’ve moved much faster and L wouldn’t have been put in a position where Light could eventually set up his win.
So they didn’t kill L, but they definitely helped create the conditions that led to his downfall by not fully backing the one person who was actually right about Kira from the start.

Why does everyone hate Near for no reason? He took risks that L didn't.

W deleted all of the data on the Kira case seconds before he died so Light couldn’t manipulate or delete any information, since he was part of the Japanese Task Force (JTF). It also meant Kira couldn’t learn about L’s successors.

Yes, L narrowed Kira’s location through the TV broadcast, and Near knew that Light had been L’s primary suspect. But the truth is the truth, L couldn’t prove it before he died. L formed too close of a bond with Light, and that was ultimately his downfall, even though he was incredibly close. Light was officially ruled out as a suspect, but Near obviously trusted his mentor and wasn’t just going to ignore years’ worth of L’s deductions because there wasn’t enough evidence to convict.

L died immediately after the Yotsuba Kira (the corporate Kira) was caught, which was exactly when L had begun suspecting Light again. Remember, Light intentionally imprisoned himself and relinquished ownership of the Death Note so he would lose his memories and be cleared using the fake rules. As soon as Higuchi was caught and Light touched the notebook again, he regained all of his memories. The Death Note was now confirmed as the murder weapon, and the existence of Shinigami was proven. Then L suddenly dies right after all of that? That’s extremely suspicious by itself.

Now put that aside for a second. L is dead, and Light conveniently takes over as “L” when the SPK is introduced. Light pretends L is still alive, but Near already knows L is dead. Light had absolutely no idea L had successors, so from Near’s perspective, how suspicious does it look that L’s main suspect is now secretly taking over L’s position while lying about L still being alive?

People act like Near just randomly knew about the notebook, but that’s simply not true.

Near learns the Death Note is in the possession of the Japanese police by interviewing officers who were present during Higuchi’s arrest. They overheard discussions about a “killer notebook.” (This wasn’t shown in the anime, it was in the manga.)
The fake L (Light/Kira) is unbelievably incompetent at catching Kira. Four to five years pass and the Kira investigation has made almost no progress at all. It’s almost like they aren’t actually trying. And whenever they do catch a “Kira,” it conveniently turns out to be another obvious decoy like the corporate Kira.
When the Director of the Japanese Police is kidnapped by Mello and is about to be exchanged for the Death Note, he is suddenly killed by Kira. Near realizes that almost nobody outside of the Task Force even knew about that exchange. That naturally makes the Task Force itself even more suspicious.
Near learns from Mello that some of the Death Note’s rules are fake. When he questions the Task Force, he discovers they have a Shinigami with them. He reasonably concludes that Kira is simply having the Shinigami lie. Because seriously… why would a literal god of death just voluntarily hang around a group of cops and tell them the complete truth?
As soon as Near publicly says he believes Kira is among the Task Force, Kira’s supporters somehow manage to discover the SPK headquarters and begin rioting outside. That’s not proof by itself, but it definitely doesn’t make the Task Force look any less suspicious.

I’ll even defend Light losing because most people say he never should have lost to Near, and I completely disagree. I loved L, but he had to die for the story to continue and to show what Kira had truly become. We watched Light manipulate his own father into dying, and he was even prepared to sacrifice his own sister if it meant protecting himself. That’s who Light became.

People also love saying Near randomly guessed Mikami was X-Kira, but that isn’t what happened.

Near suspected Mikami because of his television appearance. It wasn’t just that Mikami supported Kira, it was that he perfectly matched Kira’s ideology. He wasn’t simply defending Kira; he spoke as if he shared Kira’s exact sense of justice. On top of that, Mikami was literally a prosecutor. Think about how suspicious that is for a second. A prosecutor, someone whose entire job is enforcing justice through the legal system, openly shares the ideology of a mass murderer. That’s a huge red flag.

During that same broadcast, Mikami even used words like “delete” when referring to criminals. Kira constantly talked about “erasing” rotten people and cleansing the world, so Near notices that Mikami isn’t just another supporter, he’s speaking almost exactly like Kira.

Near already had a very strong suspicion that Light was Kira. If Light is leading the Japanese Task Force, trying to catch Kira while simultaneously proving he isn’t Kira because Near already suspects him, then he obviously can’t continue writing names himself. The logical solution is to find someone else to act as Kira.

But that person couldn’t just be any supporter. Light viewed himself as a god. He’s far too egotistical to entrust the Death Note to someone who didn’t completely share his beliefs. He needed someone who worshipped Kira’s ideology as much as he did.

Ironically, Light himself found Mikami through that same television broadcast, so it’s not some unbelievable leap that Near could make the exact same connection.

And Near didn’t magically point at Mikami and say, “Yep, that’s X-Kira.” He had Mikami placed under surveillance. The breakthrough only happened because Mello took a huge risk by kidnapping Takada, Kira’s public spokesperson. Mikami broke his normal routine to kill her himself, which led the SPK straight to the real Death Note. That one mistake exposed him as X-Kira and also revealed that there were both a fake notebook and a real notebook, allowing Near to set up the warehouse confrontation.

And sure, if you really want to argue that Near and Mello got “lucky,” the only real stroke of luck you could point to is Sidoh showing up because Ryuk had stolen his Death Note years earlier. But even then, that had nothing to do with L, Near, or Mello being handed a free win. Sidoh’s involvement was simply the consequence of Ryuk stealing his notebook long before the story reached its conclusion. He didn’t solve the case for them, expose Light, or outsmart Kira. Near still had to connect the pieces, Mello still had to take enormous risks, and Light still had to make the mistake that exposed him. If anything, Mello deserves even more credit because his actions forced Mikami to abandon his routine, which is what ultimately gave Near the opening he needed.

People give Near way too little credit. He didn’t win because of luck or plot armor. He inherited L’s suspicions, gathered years of new evidence, benefited from Mello’s reckless but crucial intervention, and patiently waited for Light’s ego to make him slip.

Near didn’t beat Light because he was smarter than L.

He beat Light because he finished the investigation L started… and because Light’s greatest weakness had always been his own arrogance. Light had SO MUCH ARROGANCE, he could have won easily making the eye deal; but through his "god complex" he wanted as much life as possible to be around to shape his "new world" Hence how "Lind. L. Taylor" was actually his first and fatal mistake; which was broadcast on television.