Time is a precious commodity, something anime understands more than most mediums. With the exceptions of a handful of shows that will outlive everyone, most anime struggle to get past a single season. While 13 (or 26) episodes might not be a lot, it is still ample time to tell most stories.
While shows like Cowboy Bebop and Gurren Lagann are perfectly paced and end at the right time, other anime series could have benefitted from lasting a while longer or even ending sooner.
10 Too Soon: Rurouni Kenshin
Starting off with a potentially controversial pick, taken on its own, Rurouni Kenshin's anime should have ended once the Kyōto Arc was done. Unfortunately, the anime caught up to the manga and, rather than take a break, decided to buy time by producing more than 30 episodes of filler. For the most part, these episodes are trash.
Due to the poor quality of these episodes, Rurouni Kenshin was canceled before it could adapt the manga's best saga, the Tokyo Arc. By overstaying its welcome, the anime wound up ending too soon.
9 Not Soon Enough: Eureka Seven
Eureka Seven is one of the best mecha and romance shows of all time. Created by Studio Bones and written by Dai Satō, who previously worked on Cowboy Bebop and Wolf's Rain, Eureka Seven is at its heart a love story between Renton Thurston and Eureka, albeit one that is set to a backdrop of intolerance, war, and political conflict.
Eureka Seven was so popular, it spawned manga adaptations and expansions, a light novel, and even video games. One of its manga, Eureka Seven: AO, was even adapted into an underwhelming anime that is not worth watching. While the franchise should have ended prior to AO, Eureka Seven also drags a touch due to lasting 50 episodes. Consequently, there are quite a few throwaway chapters that add very little, if anything, to the story.
8 Too Soon: Deadman Wonderland
Based on Jinsei Kotaoka's manga, Deadman Wonderland is just one in a neverending list of anime that should have but never got a season 2. While some series try to provide something of a satisfying ending, Deadman Wonderland concludes on a cliffhanger that will never be resolved, at least as an anime.
Set in the aftermath of a massive earthquake, Ganta Igarashi witnesses the murder of his classmates at the hands of a strange red man and is then framed for the latter's actions. Ganta ends up in a vicious prison designed to kill its prisoners as a source of entertainment. While the anime is pretty fun, very few of its central mysteries are solved, making Deadman Wonderland too unsatisfying of a watch to recommend.
7 Not Soon Enough: Riddle Story Of Devil
Sometimes, it only takes a couple of minutes to ruin an entire series. Riddle Story of Devil, aka Akuma no Riddle, centers around an assassination classroom that exists to test whether Haru Ichinose has what it takes to be the next leader of a clan. With the exception of Tokaku Azuma, the rest of the class's students are there to kill Haru.
Tokaku and Haru become close friends; however, the former's free will is constantly questioned because of the latter's "Queen Bee" power, which forces people to protect her. The last episode sees Tokaku make the hard choice to (seemingly) kill Haru, but this emotionally powerful moment is nearly instantly rendered moot when the latter is suddenly revealed to have survived. Not only that, but even other characters return from the dead, making the whole series feel pointless.
6 Too Soon: Gangsta
Gangsta is based on a still ongoing manga that is worth a read. Unfortunately, the anime's production company went out of business while the first season was airing, ensuring season 2 was never an option. The end result is an anime that feels like the first chapter in a much larger story, especially since the final episode ends on a cliffhanger.
Gangsta's European-inspired setting, its mature cast of characters, and measured storytelling deserved better than 12 episodes.
5 Not Soon Enough: Love, Chunibyo & Other Delusions!
Considering their rarity, the announcement that a beloved anime is getting a second season tends to be a cause for celebration. Exciting as it might be to spend another 12 episodes with Yūta Togashi and Rikka Takanashi, especially since the first season ends with them officially becoming a couple, Love, Chunibyo & Other Delusions -Heart Throb- feels like an exercise in timewasting.
Rather than explore the budding relationship between Rikka and Yūta, season 2 introduces a love triangle that exists simply to avoid having to deviate from the status quo. In some ways, the main characters regress throughout the season. Thankfully, 2018's Love, Chunibyo & Other Delusions! Take on Me was far better.
4 Too Soon: Bloom Into You
Due to the anime's first season only airing towards the end of 2018 and the manga concluding in 2019, there is still a decent chance that Bloom Into You will receive a second season.
Over the span of 13 episodes, the anime does a fantastic job of establishing its main characters – the emotionally distant Yuu Koito and the vulnerable Touko Nanami – while also avoiding many of the cliches that tend to run rampant in yuri series. It would be a travesty if Bloom Into You failed to earn a second season.
3 Not Soon Enough: A Certain Scientific Railgun S
Just to avoid any confusion, this entry is referring solely to the A Certain Scientific Railgun S season and not the anime series as a whole. This season is divided into the main Sisters Arc, which lasts for 16 episodes, and the filler Silent Party Arc, which spans the final eight episodes.
It cannot be stressed just how huge the drop in quality is between these two arcs. By simply existing, the Silent Party Arc diminishes the overall value of A Certain Scientific Railgun S. Along with introducing terrible villains, the Silent Party Arc repeats many of the same themes that were explored thoroughly in the Sisters Arc, making it feel redundant.
2 Too Soon: Beelzebub
To Beelzebub's credit, the anime did provide something of a conclusion once it became apparent that it would be ending after 60 episodes. While that is a healthy amount compared to nearly every other anime, Beelzebub is based on a shonen action-comedy manga that lasted almost 240 chapters. The anime only adapted around half of those.
Beelzebub is (primarily) a gag series about a high school delinquent who is charged with raising the son of the demon king who was sent to destroy Earth. As it ended before adapting the best arcs in the manga that greatly developed the story, the anime never become much more than a pretty funny comedy series with a bit of action.
1 Not Soon Enough: Darker Than Black
Darker than Black: Gemini of the Meteor might be acceptable if its predecessor did not exist. As a follow-up to Darker than Black, season 2 distances itself so much from season 1 that it barely feels like the same license. Gemini of the Meteor changes the main character for the worse, completely removes other characters from the show, and swaps the original's episodic storytelling for a serialized structure that lacks a strong enough narrative to make it work.
Gemini of the Meteor was a truly puzzling sequel that retroactively diminished its predecessor and guaranteed that a season 3 will never be made. Darker than Black should have ended at 25 episodes.