In anime, mysteries are often used to build intrigue or suspense in the plot. This is a great way to get audiences engaged, especially since it provides them with a layer of intellectual rigor and challenge. Should they theorize correctly, audiences are more inclined to feel vindicated by the time that answers are revealed.
However, there are a handful of mysteries that have never been solved. Whether due to an author's oversight or deliberate artistic choice, the questions they have left unanswered can be deeply unsatisfying to invested audiences. Some questions are even so consequential that they set the tone for the entire series.
10 No One Knows Exactly What The Void Century Entails (One Piece)
As its name suggests, the void century is a 100-year time span where all history was erased. Though little is known about what happened, one thing is certain. By the conclusion of the era, Im came to power, and the World Government's legitimacy was officially acknowledged.
It stands to reason that brutal crimes were committed and erased in order to validate the World Government's new station. Regardless, it remains a mystery until built upon further.
9 Kaiba Seemed To Be Above The Law (Yu-Gi-Oh!)
Seto Kaiba has committed atrocities against Yugi and his friends. For example, he hospitalized his father and forced his friends through a series of deadly trials. These threats included armed marines, fatal falling blocks, and even a serial killer that Joey fought in a concealed arena. When Yugi inevitably defeated Kaiba, he sentenced him to a "penalty game."
However, despite the villain's crimes being highly televised, no one thought to arrest him for attempted homicide. Although Kaiba's resources suggest he may be above the law, how he avoided prison was never clarified.
8 Superhuman Fighters Should Work For The Government (Baki)
In the Baki universe, there is a clear distinction between ordinary people and those who've pushed their bodies to superhuman lengths. The latter group is easily able to overthrow the government, having proven capable of defeating numerous armed guards at once.
The only example of a warrior working for the government is when Guevara's man helped the American president escape from Yujiro. However, considering that the agent coercively guarded his charge without their consent, this cannot be counted as a legitimate relationship between a boss and their employee.
7 The Identity Of Midoriya's Father Remains A Mystery (My Hero Academia)
Izuku Midoriya grew up without a father, which made him see All Might as a surrogate parent. After formally meeting, the two made an even stronger connection, which helped them have a strong mentor and student relationship.
However, Midoriya's biological father has never actually been addressed. Given the series' parallels with Star Wars, many fans speculate that it could be All For One, especially given his relationship with Daruma as the family physician. However, this has not been confirmed and would come across as sappy when considering Shigaraki's blood connection to Nana Shimura.
6 Notorious B.I.G Raises Consistency Issues About Stands (JoJo's Bizarre Adventure)
Carne's "Notorious B.I.G" Stand was unique for its ability to persist after its user's death. This was justified under the pretense of Carne's immense hatred toward his opponents.
While the series has contrived new rules about Stands on a whim before, B.I.G fundamentally raises a slew of complications that cannot easily be resolved. Considering that DIO's hatred of the Joestar family lasted over a century, the World should still be active despite its master's death, mindless and driven by motion.
5 Kabuto Somehow Managed To Procure An Army Of Corpses (Naruto)
The Fourth Shinobi War involved hundreds of Edo Tensei warriors clashing against the Allied Forces. However, given what the series has conveyed about resurrecting the dead, it would cause serious complications.
For example, Kabuto should have been detected at least once, having defiled numerous kage graves. Even if he managed to get away with the first grave robbing trip, tightened security should have prevented subsequent ones. It was never revealed how he stole enough living bodies to use as sacrifices for his armies. Most importantly, considering that the Edo Tensei exists in the first place, shinobi bodies should be cremated as a precaution.
4 Misa Amane's Fate After Light's Death Remained Ambiguous (Death Note)
Death Note ended almost immediately after Light's demise. Although giving viewers a glimpse of a lonely and forlorn Misa, the series does not adequately explain what happened to her.
Since she used the shinigami eyes, her life has been effectively halved. Additionally, the Japanese Task Force knew there were two Kiras at one point and that she was closely related to him. It remains unknown if Misa got arrested as an accomplice, or if she was somehow able to evade justice.
3 The Chimera Ant Race Isn't Coherent (Hunter X Hunter)
Chimera ants are supposed to reproduce through their queen. After she eats a person and any number of animals, she creates a hybrid of the two to enforce her will and the goals of the colony.
However, a second queen was not created upon the first's death. Therefore, it raises the question of where the original queen came from and if the chimera ants are inevitably doomed to extinction now that all pillars of their society have collapsed.
2 Jet's Fate Was Mocked (Avatar: The Last Airbender)
Jet was a young man whose radical ideas embodied the darker side of the rebellion against the Fire Nation. Though once a staunch opponent to Ozai, he was captured and reprogrammed by the Earth Kingdom's Dai Li. Team Avatar narrowly escaped Jet and the Dai Li in an underground encounter.
However, he was never dealt with or "cured" of his conditioning. The series itself has made fun of Jet's fate through a play recapping everything that happened up until that point. Aang and his friends were surprisingly unconcerned that Jet may have suffered a fate worse than death.
1 Paradis' Ultimate Fate Remains A Mystery (Attack On Titan)
After the Rumbling, Paradis and the remaining world population had an uneasy truce for a time. However, the vengeful families of the fallen later visited the island and bombed it into smoldering rubble.
It is strongly implied that the Source of All Living Matter, what gave Ymir her original powers, reawakened as a result of this carnage. However, audiences never saw the final fate of Paradis, if the titans returned, or if the Eldians finally went extinct, something they desperately fought to avoid.