In the film industry, prequels are often seen as taboo. Viewers believe there's no reason to expand on an existing story, especially when they believe they already know how it turns out. However, with anime, knowing how it turns out isn't necessarily a bad thing.
Most long-running anime often set up these massive universes with dozens of characters, and better series also give a glimpse into the histories of these characters. It's these glimpses into the past that often leave fans wondering exactly what happens, and in the case of many shonen anime, there's plenty of potential for new stories.
9 Yu Yu Hakusho: It Could Focus On The Earlier Spirit Detectives
When Yu Yu Hakusho begins, it focuses on a young street punk who's been pulled into the world of interdimensional politics when he's assigned the role of Spirit Detective. Before Yusuke Urameshi took on that role, though, it fell into the hands of multiple other characters.
A Yu Yu Hakusho prequel should take the time to look at what happened to Genkai and Toguro in their youth, and what eventually led Toguro to seek strength above everything else. Or it could take another route and focus on Shinobu Sensui, a much more tragic figure who tried to be the perfect Spirit Detective but fell apart after seeing the depths humanity could fall to.
8 Black Clover: It Should Give A Look At Yami's Early History
Black Clover is fascinating as a story about class conflict and seeing a rigidly stratified world gradually broken down by the efforts of both royals and commoners. But a prequel would be great if it gave viewers a glimpse into Yami Sukehiro's life.
Yami has said he comes from a country that's not connected to the four countries in the anime at all. A series focused on his life could give viewers a chance to see what that country is like but also track his journey from becoming a Magic Knight to becoming a top member of the Grey Deer and eventually being given his own guild.
7 Assassination Classroom: Fans Would Love To See Koro-Sensei Before He Was A Teacher
Assassination Classroom focuses on a friendlier side of this universe, with Koro-sensei raising a bunch of middle-school children and preparing them for the real world. Everything winds up with a mostly happy ending, and viewers are able to see all of them go on to live productive lives after graduation.
But there was a much darker side to the world of Assassination Classroom that the series talked about but never focused on. Before Koro-sensei was a teacher, he was the deadliest assassin who ever lived. Showing his story and some of the jobs he did while he was in a world of darkness would be an extreme shift, but not much from what viewers experienced whenever new assassin characters were brought in to defeat him when he was a teacher.
6 Gintama: It Would Be Great To See The Past Before Humanity Started Working With Aliens
Gintama is one of the few shonen series that's pretty complete from start to finish. By the end of the story, most of the questions people have about all of the characters are pretty much answered, even though fans might want more of the characters. But the universe established is so vast that it's hard to let it go.
A prequel could focus on the rest of the world when it was suddenly discovered by aliens. It would instead deal with how they fought back until they all agreed it would be better to simply work with the aliens than continue to fight against a threat they couldn't beat. Rather than center on Gintoki, it could focus on many of the other characters established in the series instead, such as Kagura's dad.
5 Case Closed: Fans Would Love To See Kudo Before He Was Turned Into A Kid
Case Closed has a very straightforward plot that it's been using for the past two decades. Shinichi Kudo is a genius teen detective who spent his days solving crimes until he ran into the wrong criminal organization. Originally, the organization tries to wipe Shinichi out, but their attempt to kill him fails, and instead, he's turned into a young child.
The series has run long enough with Kudo that he's flipped back and forth between ages. However, that doesn't mean it wouldn't be entertaining to see a short series that focused on him before he was subjected to that mysterious drug. Even better, a story showing how his parents first met and fell in love would be something most fans wouldn't want to pass up.
4 Demon Slayer: The History Of The Demon Slayer Corps Deserves To Be Expanded On
In the manga, the story of Demon Slayer has been over for a year now. The characters have reached their conclusion, and for better or worse, everyone has moved on. But while many manga readers believe the story has been rushed, there's no way to fix that with a sequel. Ideally, the people in the future get to enjoy an era of peace.
The best way to flesh out the story now is by showing more of the past. How did Muzan become a demon? Who was the person who created the initial sword style that was capable of fighting demons? Where did the original Hashira Swordsmen come from? Some of this is in the manga, but a mini-series adding more to this storyline would be adored by fans everywhere.
3 Kenichi: History's Greatest Disciple: Kenichi's Teachers Need Their Own Story Told
History's Greatest Disciple: Kenichi is about a helpless young boy named Kenichi who decides to start training to defend himself. He has no talent, but he's constantly learning from martial arts trainers who are so impressive that they're literally superhuman.
Though the anime hasn't had a proper adaptation and could use a remake, until then, it would be nice to tell the story of all the martial artists who Kenichi trains under. Though they play a larger role in the manga, those moments still largely focused on the present rather than a glimpse into their histories.
2 Fullmetal Alchemist: Brotherhood: Colonel Mustang Could Easily Carry His Own Storyline
The entire focus of Fullmetal Alchemist is about Edward Elric and his brother trying to find the Philosopher's Stone to restore their bodies. But like any good story, the world in the background is fleshed out as well. Edward becomes a "dog of the military," which indicates the military doesn't have the best reputation.
In the later parts of Brotherhood, viewers learn the country is deeply scarred after a major war that happened not too long ago. Getting to see Mustang and Maes Hughes in the muck that leads to Mustang deciding to run the country is one direction a prequel could take. Getting to see Ed and Al's dad as he journeys across the country is another, and both are great directions.
1 Naruto: The Formation Of The Leaf Deserves An Entire Series To Itself
Naruto already has a sequel about the next generation of ninja. But a Naruto prequel might have actually been the way to go. There are dozens of stories that are begging to be delved into from the franchise's early history.
To begin with, showing the war between the Hashirama and Uchiha clans is already something most fans have wanted to see. If nothing else, getting to see the founding of Konoha and how they managed to bring in all the other clans is something that would have Naruto fans everywhere eagerly awaiting every episode.