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Countless anime go down in history for their iconic multi-season runs, but some of the most promising stories are ruined by an unforgivable second season. While length isn't necessarily a foolproof marker of quality, there are plenty of long-running anime that keep getting better, year after year. Granted, the longer an anime goes, the more opportunities it has to fail. Be it an out-of-place twist, an underwhelming battle sequence, an abundance of filler episodes, etc., even the most beloved anime fall victim to the genre's most common mistakes.
Conversely, there are plenty of beginner-friendly anime that new fans can binge in one weekend. In rare cases, only a single batch of episodes is necessary to tell a comprehensive story, and one-season wonders often go down in history as easily digestible, entertaining, bite-sized chunks of drama, romance, or good old-fashioned action. In the modern age, more and more series are being conceptualized as single-season narratives, but classic anime fans still prefer a show they can root for. As such, up-and-coming titles often fight tooth-and-nail to be renewed— even if creating a second season can be an anime's greatest blunder.
Tower of God
The Second Entry Seemingly Lost Everything That Made It Unique
Based on the 2010 webtoon of the same name, Tower of God follows a boy named Bam who ventures into the eponymous tower in search of his best friend, Rachel. On each floor, however, Bam faces unimaginable trials alongside hundreds of other contestants, ranging from a convoluted game of tag to an all-out death match. Along the way, Bam finds himself forming unlikely alliances, friendships, and hostile rifts as the tower's deadly politics begin taking hold.
Despite the intriguing premise and impressive first season, Tower of God quickly joined the ever-growing list of hit anime that fell off from season 2 onward. In the second installment, Tower of God adopted an entirely different art style, which most viewers noted as a major downgrade. Season 1's distinctiveness, while divisive, made the anime stand out. Consequently, season 2's generic, borderline unidentifiable art did a grave disservice to the story. Similarly, Tower of God season 2 simply felt smaller, with less detailed backgrounds and jarring editing cuts working against the high standards that season 1 set.
One-Punch Man
A Major Downgrade From A Stellar First Season
One-Punch Man is a particularly peculiar case, as its second season isn't objectively terrible, but it's a marked demotion from its first installment. When it originally aired in 2015, One-Punch Man felt like an instant classic. The hilarious titular superhero, Saitama, was an immediately iconic character thanks to his quirky character design and endearing personality. Sadly, One-Punch Man season 2 felt like a giant step in the wrong direction.
Like Tower of God, One-Punch Man overhauled their original art style, sacrificing the appeal of the strong imagery and detailed fight scenes. In their place were blurry, almost comically bad showdowns that lacked the gravitas manga readers expected. Regardless, the actual story was handled fairly well. As such, though many believe the One-Punch Man anime was a failure, it's still leagues above many of its contemporaries.
The Rising of the Shield Hero
A Disjointed Collection Of Skipped Arcs & Glaring Plot Holes
Following an incredibly successful debut in 2019, The Rising of the Shield Hero was on the road to becoming an acclaimed isekai anime. College student Naofumi Iwatani was merely reading a book when his true destiny as the eponymous Shield Hero summoned him to a magical world. The underdog slowly learned the lay of the land, gradually building towards a make-or-break battle with a corrupt family of nobles. After an overwhelmingly positive reaction from the viewers, The Rising of the Shield Hero began developing season 2.
As soon as the second season premiere aired, however, it became abundantly clear that The Rising of the Shield Hero had lost its touch. At once, the show dragged in places while feeling rushed in others. Furthermore, season 2 ambitiously attempted to cover so much of the source material, it ended up overlooking some of the most important story beats. Even if viewers could have forgiven the narrative transgressions, though, the three-year wait added insult to injury and robbed The Rising of the Shield Hero of earning modern classic status.
Aldnoah.Zero
A Second Installment That Tragically Undercut Season 1's Best Moments
Aldnoah.Zero may be one of the most painful anime with wasted potential. The visionary sci-fi series followed an alternate history where humans found a "Hypergate" on the moon, allowing them to create a new civilization on Mars. The first season picked up during an intense war between the remaining Earthlings and the far advanced Vers empire, culminating in a climactic finale wherein numerous major characters died.
Yet, when Aldnoah.Zero returned for a second season, its epic ending was immediately retconned. The characters who died in battle were unilaterally revived for no clear reason aside from fan service, making it seem as though the anime lacked the courage to stand behind its original story. Additionally, the enthralling characters suddenly felt diluted, which detracted from the anime's one-of-a-kind worldbuilding and left viewers in a state of pure confusion.
Tokyo Ghoul
A Disappointing Blip In An Otherwise Iconic Franchise
Over a decade later, Tokyo Ghoul's influence can still be felt far and wide in the horror genre. The concept of cannibalistic ghouls walking amongst us was as fascinating as it was terrifying. To complicate matters further, protagonist Ken Kaneki was turned into a half-ghoul after a harrowing near-death experience, meaning he retained his humanity and the guilt that comes with it, but it isn't strong enough to drown out his hunger for human flesh.
Ken Kaneki was added to the video game Dead by Daylight in April 2025 as a playable killer known as The Ghoul.
Though the first installment was a full-blown cultural phenomenon, it's widely agreed that season 2 ruined Tokyo Ghoul. In an unprecedented move, the anime's second entry abandoned its source material entirely to tell an original story. Unfortunately, it was a risk that failed to pay off, and it squandered the good standing earned by Tokyo Ghoul's pilot season. The show attempted to recalibrate in its third season, but the anime never truly recovered from its disastrous sophomore year.
The Devil is a Part-Timer!
An Entirely Different Art Style Alienated OG Fans
The Devil is a Part-Timer! had everything going for it. Whether you loved supernatural anime, slice-of-life hijinks, or just a quirky ensemble cast, The Devil is a Part-Timer! seemed like a reverse isekai story for the ages. As the title suggests, the anime follows Satan (going by the name Sadao Maō) as he starts working at a "MgRonald" fast-food restaurant to protect his human disguise.
The Devil is a Part-Timer! season 2, in contrast, forgoes its demonic action subplots and natural comedy for an extremely forced found family arc. The second installment suddenly introduces Alas Ramus, a child who literally appears out of nowhere but becomes the driving force behind the entire season. Everything that made season 1 so special was either dialed down or forgotten completely, and fans mourn the anime's true potential to this day.
Black Butler
A Failed Experiment That Abandoned The Canon Source Material
Without a doubt, Black Butler was a defining anime of the late 2000s/early 2010s. The unconventional dynamic between the crime-solving Earl Ciel Phantomhive and his demon servant Sebastian was downright inimitable, and the tense underlying plot of Sebastian wanting to consume Ciel's soul kept viewers on the edge of their seat.
Nevertheless, even a masterpiece revenge anime like Black Butler can take a dive with its second season. In this case, the series completely diverged from its source material, added unnecessary side characters, and had another demon steal Ciel's soul in one of the most unsatisfying twists in anime history. Thankfully, the fandom— and, ironically, the show itself— basically pretend season 2 never happened, as Black Butler season 3 gets the story back on track.
The Promised Neverland
An Infamously Underwhelming Sophomore Season
Unquestionably, The Promised Neverland season 2 is the worst anime sequel ever created. The supernatural thriller was a must-watch anime after its first 12 episodes thanks to its high-octane storyline and unrivaled tension. The survival drama followed a group of orphans escaping their seemingly perfect life after uncovering the dark truth: they were being raised on a human cattle farm to be fed to demons.
Whereas the first showing fleshed out the main characters and had them truly earn their freedom, The Promised Neverland season 2 was a walk in the park, as every time the crew found themselves in danger, they would conveniently make it out unscathed. The most egregious indiscretion, however, is skipping what's universally considered to be the best arc in the manga. As a result, there were multiple villains, subplots, and overarching pieces of lore that the anime left out entirely. Yet, even viewers who never read the source material recognized that The Promised Neverland season 2 was a total flop.
