In recent years, a good deal of anime have done a wonderful job of exceeding the expectations set by the popular manga they're adapting. Demon Slayer is a great example. With the use of amazing animations and extended scenes, Ufotable has enhanced the already amazing story. But the same cannot be said about all anime.
Over the years, there have been many amazing manga that, unfortunately, were abandoned by their adaptations. Some fail to translate action and emotion due to poor animation and art style. While some stories lost their essence because important arcs were poorly done or left out altogether. The following are 10 anime adaptations that failed to give their source material the adaptation it deserved.
7 Classic Shonen Anime That Are Totally Unwatchable Today
You will have a hard time watching these classic shonen anime today.
Claymore
Claymore is loved by its fans, and many consider it a great anime, if not for the last two episodes. Unfortunately, the anime fell victim to the times. During the anime's run, it caught up with the manga and was forced to create an original ending for its final episodes. This led to an ending that felt abrupt and unsatisfying. The manga eventually continued to be much longer and had a more convincing and happy ending.
A punch man
With over 35 million copies in sales, the One Punch Man manga has certainly been a success. Initially, its adaptation was also a great success. The first season of the anime was released in the fall of 2015 and immediately became a fan favorite worldwide. It was fully animated with proper attention to character design and epic fight scenes. This set up great anticipation for the upcoming sequels.
But when season 2 came out 4 years later, it was disappointing to many fans due to the change in art style. With the arrival of season 3, things got worse. What was once considered a comedic masterpiece is now limited to failed sequels.
Soul Eater
Soul Eater is by no means a bad anime; Fans all over the world love and adore it. This is a great story with lots of fun characters. But when compared to the manga, one can't help but notice the obvious differences. A major part of the story was the collection of souls. While the manga had a list that allowed which spirits could be hunted, the anime changed that and introduced “kishin eggs” instead.
But more importantly, the second half of the anime moves far away from the manga and has its own ending. Many fans still consider the manga to have good pacing and a good ending.
Flowers of Evil
Its readers love the Flowers of Evil manga. They describe it as a great psychological manga that is character-driven and explores the gruesome side of teenage behavior. It's strange and uncomfortable but real. Anime is a rare place where it manages to carry that tone, but most viewers don't like it.
The anime was produced using retroscoping, which drastically changed its art style from the manga. Often, the characters lack the necessary details, and the art style loses notable features, making them look alien compared to the manga. While some viewers enjoyed it because it added to the weirdness of the anime, many viewers hated it because it made it unwatchable.
Deadman's Wonderland
Deadman Wonderland is a popular show of 2011. While some fans seem to enjoy this dark-toned anime, it ends abruptly, and they are never given a proper ending. When compared to the manga, the flaws start to become apparent. First, the anime struggles with poor pacing. It moves too quickly from one event to the next without leaving enough explanation or context.
Another problem is that, due to the limited number of episodes, the anime decided to leave out many characters that appear in the early chapters of the manga. It also changes aspects of the character or replaces them with a completely different character. This changed the overall feel of the plot. The ending of the anime was much earlier than the manga, which made it feel rushed and unfinished.
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Rosario + Vampire
The first season of Rosario + Vampire is what the manga delivered. The anime begins as a rom-com slice of life harem with fan service and continues until the end. While this is true for the manga in the beginning, it soon evolves into a better story. The manga includes chapters focusing on main character development and training and fight scenes. It quickly builds into a fighting shonen that fans appreciate and enjoy.
But the anime failed to adapt to this development and diverged from the manga, creating a plot that felt very different from what the manga intended.
Berserk
The Berserk manga has, as of 2025, sold over 70 million copies, placing it among the top 50 best-selling manga of all time. The show first received an adaptation in 1997, which is still well regarded. But the next season, which was produced between 2016 and 2017, was hated by fans. Mainly because of the animation.
The anime's poor CGI and out-of-place sound design make the revenge warrior story feel extremely weak. To make things worse, the anime also skipped arcs that included necessary character development.
Uzumaki
Junji Ito's horror masterpiece waited years for a suitable adaptation. In 2019, fans rejoiced when an Uzumaki adaptation was announced. When the first episode of the anime was released, it was met with praise and excitement. Fans were thrilled to finally see this beloved horror manga in animated form. But when the second episode came out, all the praise and excitement was met with serious disappointment.
The quality of the animation had dropped drastically, making it a laughing stock on the internet. But another issue not talked about in the Uzumaki anime was its pacing. Uzumaki is a relatively short story, but only 4 episodes was not enough time to create the right atmosphere for such an unstable story. Events in the anime happen very quickly instead of the slow and terrifying pace that good horror anime is known for.
The Promised Neverland
The Promised Neverland manga, during its four-year run, has sold nearly 42 million copies. The manga had an interesting and unique premise and built a large world with a large cast of characters. There was a lot of action, character development, and world-building that made this a fun manga to read.
The anime adaptation got off to a great start with an initial season that set the stage for what was to be many epic seasons of great storytelling. But sadly, Season 2 dashed fans' hopes by leaving behind an integral and beloved arc. It went ahead and made changes and ended up completely straying from the manga's intentions. Important characters were left out, and what could have been at least four seasons of great storytelling was forced into a finale that failed to make sense.
Tokyo Ghoul
It's no surprise that Tokyo Ghoul is finishing this list. Over the years, the Tokyo Ghoul series has been remembered as one of the biggest adaptation failures in anime. The first season ran through the manga, skipping events, and instead focused on action. While not perfect, the first season was still fun for many fans. But with the second season, things became unacceptable because the anime had strayed too far from the manga. It ended up being non-canon while continuing to drop arcs, which made things confusing.
Finally, the last two seasons had similar problems. Skipped chapters led to events and relationships that didn't make sense. The animation had also dropped by this point, and everything felt rushed. Considering how good the manga is, it's a real shame that this amazing story never got a proper anime.
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These anime had a lot of potential, which is evident from their manga. Production issues, time constraints, and various issues resulted in some of the most disappointing anime we've ever seen. Fans can only hope that, eventually, their beloved manga can get adaptations that stay true to the manga and give us shows that truly celebrate these wonderful stories.
