Adapting a manga for an anime series or movie is tricky. Most of an adaptation's challenges come from the reality that translating a serialized story into a wholly different medium with a set runtime is, simply put, arduous. Some anime solve this by making necessary creative changes, while others just chuck the source material out.

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Unlike polarizing anime like Berserk (2016) or Tokyo Ghoul √A which can still (barely) pass for bad or questionable adaptations, some anime changed or left out so much that they could count as original works with tenuous connections to a pre-existing manga. In the end, all that remained of the original manga were a few names and concepts.

10 Gantz Ended Where The Manga's Real Story Only Began

Gantz

Kei Masaru and Megumi wait for the game in Gantz

Gantz is infamous for being one of the bloodiest ultraviolent anime of the 2000s, but if it were a complete adaptation of Hiroya Oku's tech-filled Gantz, it would've been darker and gorier. The anime ended with the Buddhist Temple Alien Mission, wherein most of the characters died, and Kei was the sole survivor who may or may not have been run over by a train.

Not only does the manga not have the anime's notoriously confusing ending, but it ballooned in scope and gore. The Buddhist Temple was the first of more increasingly deadly missions, which were actually preparations for the alien invasion that the Gantz players were covertly being trained for. If the anime was just a death game, the manga was a cosmic epic.

9 Shadow Star Stopped At The Manga's Start Of Darkness

Shadow Star

Shiina spends time with Hoshimaru in Shadow Star

To most anime fans, Shadow Star (or Narutaru) is nothing more than that dark deconstruction of monster anime like Pokémon. The anime began with Shiina adopting a cute creature she named Hoshimaru, and things got worse afterward. In fact, Shadow Star ended with Shiina killing her friend to prevent a monster-led massacre.

Believe it or not, the anime only covered the manga's first act, and things got even worse and more surreal later on. As Mohiro Kitoh's deconstruction of monster stories went on, it evolved into a cosmic horror that culminated with Shiina ending the world. The anime may come across as an edgy takedown of Pokémon, but the manga is on another surreal level.

8 Akira Left Out The Manga's Post-Apocalyptic Epic

Akira

Kaneda saves the last of Tetsuo essence in Akira.

Akira isn't just one of the most critically-revered works of animations ever put on the big screen, but it's also one of the most impressively detailed forms of manga ever printed. Katsuhiro Otomo's Akira is an epic in every sense of the word, and it spans six volumes with over 2000 pages of characters, story, and world-building.

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For practicality's sake, Akira's scale and scope were trimmed down for the big screen. The movie adapted the manga's first half and completely did away with the post-apocalyptic society that emerged after Tetsuo burned Neo-Tokyo to the ground. If Akira ended with Neo-Tokyo's destruction, this was only the beginning of the manga.

7 Eat-Man Did Away With The Manga's Fantasy Trappings

Eat-Man

Bolt Crank aims his pistol in Eat Man

To most old-school anime fans, Eat-Man was just another dark sci-fi dystopia that was traversed by a badass. In Eat-Man's case, Bolt Crank was an immovable mercenary best known for his ability to eat anything and summon it later. But if the anime was a generic sci-fi story, Akihito Yoshitomi's manga was actually a dark fantasy.

Eat-Man was a mix of sci-fi and fantasy, but Studio Deen's anime focused on the sci-fi since that was the big fad in the '90s. As a result, most of Eat-Man's mysteries didn't make sense, and there were too many dangling threads to tie up. After intense backlash from fans, a more faithful and fantastical adaptation in Eat-Man '98 was released.

6 Rosario+Vampire Capu2 Ditched The Manga's Subtext For Ecchi Shenanigans

Rosario+Vampire

The girls fight over Tsukune in Rosario Vampire

The 2000s were simultaneously some of anime's best and most controversial years since the medium enjoyed a surge in popularity while also enduring backlash for the wave of ecchi shows it pumped out. One of these ecchi series was Rosario+Vampire, a raunchy supernatural-themed romp that was a far cry from the manga.

Rosario+Vampire's first season was a more lighthearted but still broadly faithful adaptation of mangaka Akihisa Ikeda's mix of fanservice plus themes of racism between humans and yokai. Meanwhile, the second season (or Capu2) devolved into a full-on ecchi show. As a result, the first season's attempts at depth were rendered pointless.

5 The Promised Neverland Season 2 Replaced 100 Chapters With New Material

The Promised Neverland

Ray and Emma gather their bearings in The Promised Neverland

One of the most baffling things about The Promised Neverland was that it started out as one of the best anime adaptations of the 2010s, only for it to ignore writer Kaiu Shirai and illustrator Posuka Demizu's critically acclaimed manga. For whatever reason, CloverWorks created a new, worse story for the Grace Field kids.

Despite a few deviations from the manga, The Promised Neverland Season 2 started faithfully enough before diverging into CloverWorks' retelling of the conflict between man and Demon. To make matters worse, Season 2's notoriously simple story and morals replaced nearly 100 chapters' worth of intricate characterizations and world-building.

4 Fullmetal Alchemist Gave Amestris A New Conspiracy & History

Fullmetal Alchemist (2003)

Edward and Alphonse Elric as seen in Fullmetal Alchemist

In both incarnations of Fullmetal Alchemist, the country of Amestris was the epicenter and victim of a centuries-spanning conspiracy instigated by a mysterious power-hungry alchemist. However, the central antagonist varied between anime. The first anime featured the anime-only villain Dante, while the reboot Brotherhood had the text-accurate Father.

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Since Fullmetal Alchemist's first anime was made when the manga was far from done, mangaka Hiromu Arakawa allowed Bones to tell their own story. Bones' anime was faithful up until the nightmarish incident involving the Chimera, but because of Dante's machinations, even the adapted characters and stories had a new context.

3 Hellsing Had No Choice But To Create An Entirely New Conflict

Hellsing (2001)

Alucard searches and destroys in Hellsing

The 10-part Hellsing Ultimate may be one of the best OVA series ever made and the Hellsing that fans know and love, but it wasn't the first time that Kouta Hirano's manga was adapated. In 2001, Hellsing was brought to life in an anime that's arguably more of a workplace horror than the Gothic war story of the manga and OVAs.

Hellsing was adapted when the manga wasn't even halfway done, thus forcing studio Gonzo to write their own story. Gonzo's continuity focused on the Hellsing Organization's inner workings and personnel, and it also mediated on some characters' vampiric immortality. The OVAs did these too, but they focused more on the epic-scaled bloodshed.

2 Metropolis Is An Amalgamation Of Osamu Tezuka's Ideas, Not A Manga Adaptation

Metropolis (2001)

Kenichi tries to save Tima in Metropolis

In 1949, Osamu Tezuka made Metropolis, a sci-fi manga about the life and tragic death of the android Mitchi. The manga was technically adapted into a movie in 2001 since only its title and a few key concepts remained intact. Instead, Metropolis was more of a mixture of Tezuka's stories and signature themes.

Unlike Tezuka's manga, the Metropolis anime focused on dystopian social unrest, and Tima (Mitchi's stand-in) was more of a plot device. In brief, Metropolis was more of a gritty Astro Boy update than a manga adaptation. To be fair, Metropolis itself was a loose adaptation of Fritz Lang's movie of the same name, and the anime movie kept this tradition alive.

1 Yu-Gi-Oh! Turned A Sidestory Into An Anime & Gaming Franchise

Yu-Gi-Oh!

Yami draws his next card in Yu Gi Oh Duel Monsters

In Kazuki Takahashi's manga Yu-Gi-Oh!, the spirit of the ancient pharaoh Atem (or Yami) challenged opponents to dark and deadly Shadow Games. The games changed in each arc, although the "Duel Monsters" card game proved to be so popular that it was used as the basis for a massively successful anime and a real-world trading card game.

Yu-Gi-Oh! Duel Monsters focused solely on the Duel Monsters card game, and it used the manga's events more as a guideline for storylines instead of adapting them. A text-accurate adaptation of the manga exists in the colloquially named "Season 0," although it was supplanted by the infinitely more popular and influential Duel Monsters.

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