For every unforgettable series, there are a dozen more forgettable ones. The sheer amount of anime released each year basically guarantees this as a fact of life, but there are some series that build significant hype and large fanbases as they air, only to vanish from conversation later, slipping from the collective otaku memory without warning.
Whatever genuine charms these shows have, they have failed to stand the test of time or endear themselves to new fans. While shonen series like One Piece, Hunter X Hunter, and Naruto have only gained popularity over the decades, there are some series that fall just short of classic.
10 Katekyo Hitman Reborn! Strayed Away From What Made It Unique
Once lauded as a beloved shonen favorite of the early 2000s, it's rare to hear any mention of Reborn! in the decades that followed. The series about a boy inheriting a mafia boss title was was hugely popular. Initially an offbeat entry in the subgenre, fans enjoyed the humor and oddball antics of the main cast. As the series progressed and became more pseudo-serious, it lost some of the allure which made it unique, devolving into battle-shonen clichés. The failure of the producers to release rights to the series overseas led to a debacle between fansubbers and Funimation that may also have hampered the show's success.
9 Kenichi: The Mightiest Disciple Features A Relatable Protagonist But Is A Little Unoriginal
Now primarily referenced for its terrible depictions of female character design, in its heyday, Kenichi earned many devoted fans. Kenichi is a relatable protagonist who becomes determined to study karate after relentless bullying.
Grounded in real-world martial arts despite anime tropes, Kenichi is a series worth checking out, albeit a little unoriginal. The manga has over 12 million copies in circulation, but the world rights have since lapsed.
8 Blue Exorcist Had A Five-Year Delay Between Seasons
Ao No Exorcist's first season was an overwhelming success that soon spawned a feature film and encouraged increased printings of the manga. The premise is classic shonen gold that plays off several world mythologies. Rin Okamura is manifesting his powers as the son of satan, and his twin brother becomes his keeper as he transfers to an exorcist training academy. The first season of the anime was an adventurous romp that caught up to its source material too soon, resulting in a botched ending that lacked the nuance of the non-filler episodes. And during the massive 5-year delay between the first and second seasons, fan enthusiasm seemed to evaporate.
7 Major Doesn't Stand Out Among Other Popular Sports Anime
There are more than 150 episodes of the baseball anime Major, but few modern sports anime fans outside of Japan mention the series alongside fabled titles like Prince of Tennis and The Big Wind-Up.
This is not to say that Major isn't a great show. The story of Goro Handa's journey from childhood little leaguer to professional baseball player is often rewarding and carefully written. The manga has won numerous awards, but somehow the series has failed to garner worldwide popular success in the same manner as Kuroko's Basketball or Haikyuu!!.
6 Nabari No Ou Features Ninja & A Reluctant Hero
Nabari No Ou hit screens just past the peak of the world's emo phase, in 2008. Perhaps if it had aired just a couple of years before, in the era of Death Note, it would have faired better with audiences. The main character Miharu Rokujo is thrust into the world of ninja after learning his body contains a powerful ninja scroll. The definition of a reluctant hero, Miharu wants nothing to do with this power, and perhaps his reticence as a character has something to do with the series remaining mostly a sleeper hit. Fans are used to more enthusiastic ninja and more likable leads.
5 Beelzebub Was Canceled Early
One has to wonder how much of Beelzebub's failure to succeed in America has to do with the fact that it features a constantly naked demonic baby in one of two lead roles. But the show is genuinely funny, a curious mix of delinquent fighting tropes and babysitting, and ran for 60 episodes before a premature cancellation.
When high school delinquent Tatsumi Oga finds himself tasked with raising the infant son of the demon king, all manner of chaos ensues as the two troublesome characters bond and fight demons together. Due to problems in the production and reception of the series, the manga was canceled early as well.
4 Chrome-Shelled Regios Mimicked Other Successful Anime & Became Unoriginal
The shonen genre went through some growing pains between 2000 and 2013 when Attack on Titan largely redefined what the subgenre was capable of. Chrome-Shelled Regios feels like an attempt to mirror the success of Code Geass, but Code Geass already existed as a series that borrowed heavily from other shows. In general, Chrome-Shelled Regios is forgettable because it is a shallow amalgamation of tropes that were already tired: holy knights in a post-apocalyptic world, needlessly complicated world-building, magical school, a protagonist with secret powers. These days, there's little reason to look back on series like this, which were truly ten a penny.
3 Nyan Koi Has A Unique Concept Involving Cat Allergies
Nyan Koi has most of the elements that should make it popular even a decade after airing. The series focuses on Junpei Kosaka, a boy who is allergic to and disdainful of cats but is nonetheless granted the ability to understand cat-language. In a bizarre twist of fate, if he doesn't grant cats 100 wishes, he himself will transform into a cat and die from his own cat allergy. More cutesy than substantial, the goofy premise leans too far into harem clichés and is never played out as satisfyingly as it could be.
2 Pandora Hearts Has Highly-Stylized Designs But Lacks An Identity
In the wake of Fullmetal Alchemist's profound and well-deserved success, several mediocre imitations attempted to capture the same audience. Among these was Pandora Hearts, a story blatantly inspired by Alice in Wonderland, which focused on the convoluted exploits of a boy who becomes trapped in an alternate world during his coming-of-age ceremony. Overwritten, needlessly dark, and at times convoluted, the series lacks an identity of its own but won some fans due to its highly-stylized designs.
1 The World God Only Knows Was Once The Most Popular Harem
How did a series go from the world's most popular harem franchise to almost forgotten in less than a decade? Whatever staying power propels some series to the annals of anime fame is lacking in The World God Only Knows. Beautifully animated but more than a little formulaic, the show initially won fans over with sheer panache. When teenage gamer Keima Katsuragi is approached by a spirit who asks him to help her free evil spirits from the hearts of girls, he excels in the role due to his skill as a galge player. He conquers the girl's hearts using methods learned in dating sims, and soon a harem forms around him. If the premise sounds problematic, that's because it is. But despite the icky idea that women can be won over using shallow gaming tactics, the show has some moments of genuine pathos.