Not everything is meant to be experienced twice.
Some anime are just not rewatchable. This often goes for series anime fans watched when they were still getting into the medium — at that point, everything is good.
While most of these are still not bad at all, they all suffer from problems that tend to annoy experienced fans — and said fans should never rewatch them if they want to keep their fond memories of them.
The Future Diary (2011)
This is the poster child for non-rewatchable anime. The Future Diary (Mirai Nikki) surprises viewers with violence, brutal deaths, insane plot twists and a crazy yandere female lead.
Sadly, these aren’t things that usually appeal to older anime fans. Many who rewatched the anime felt it was just overly edgy and full of plot holes, and definitely not as impressive as they initially remembered.
The Seven Deadly Sins (2014–2021)
Among the popular shounen series of the 2010s, The Seven Deadly Sins (Nanatsu no Taizai) arguably aged worse than anything else. The amount of fanservice doesn’t help, as the audience doesn’t really overlap with ecchi fans.
The later seasons have significantly worse animation, and the arcs they cover aren’t even good. If you are going to rewatch it, perhaps it’s a good idea to stop after Season 1.
Code Geass (2006–2008)
It’s hard to rewatch Code Geass: Lelouch of the Rebellion (Code Geass: Hangyaku no Lelouch), especially considering where the franchise has been going recently. The original anime was praised for its amazing finale (of S2), which was retconned in the movies and sequels.
As if that’s not enough, the main selling points of the anime are its plot twists and genius protagonist. The plot twists don’t hit as well when you know them in advance, and Lelouch is smart, yes; but a lot of his opponents aren’t, and him outsmarting dumb people isn’t really something interesting to watch.
Naruto (2002–2017)
It is already hard to rewatch long series due to time commitment. Long-running battle shounen series only make the problem worse, and arguably the worst one for a full rewatch is Naruto. The anime has a ton of flashbacks (sometimes with other flashbacks), and the pacing is uneven, but that’s not even the worst problem.
The fillers are nearly impossible to rewatch, and many advise to skip them if you’ve already seen them. The hardest part is getting through around a hundred episodes at the end of the original series, almost none of which impact the plot.
Death Note (2006)
Death Note’s issue is similar to that of Code Geass. While the anime is quite good at writing actual genius characters, their behavior is still very over-the-top, and older fans often prefer realistic and grounded takes on the mystery genre.
Another issue with Death Note is its last cour, which, to many, feels like a downgrade in quality. While on the first watch, you might not have minded much, you’d be more annoyed on the second one if you already disliked it.
Golden Time (2013)
Romantic comedies tend to be hit or miss, and Golden Time was a go-to recommendation for the genre around a decade ago. It was often recommended alongside Toradora!, which it shares an author and some of the cast with.
Unfortunately, Golden Time has much more misunderstandings and plot contrivances, and it simply doesn’t hold up on a rewatch.
Your Name (2016)
A lot of otaku say that Makoto Shinkai’s movies are made to be watched on the big screen. That’s certainly true for Your Name (Kimi no Na wa.), which is still his most beloved movie. It’s breathtakingly gorgeous, and it’s understandable why it instantly got so popular after release.
Unfortunately, this “wow” fact can’t really be achieved twice, and the movie leaves some questions unanswered. Not to mention that watching it on a PC screen (or even on TV) wouldn’t be as good as in a theater.
Soul Eater (2008)
A series that used to be a go-to recommendation for shorter battle shounen, Soul Eater is still considered iconic. Its popularity was the reason for the other work of the mangaka — Fire Force (Enen no Shouboutai) — being as popular as it is.
Sadly, Soul Eater itself has a major issue — its finale is entirely anime-original, and, frankly, somewhat silly on a rewatch.
Sword Art Online (2012–2020)
Many people started watching anime thanks to Sword Art Online. As such, they’re still grateful to the series that got them there back in the day. Unfortunately, SAO definitely doesn’t stand the test of time. While it’s not necessarily terrible, it’s not as good as it might have seemed ten years ago.
Sword Art Online is notorious for its high peaks and really bad lows — and the latter attract a lot of haters. While the hate is definitely overblown, the anime is still mostly average in the end.
One Punch Man (2015–2019)
It’s really hard to rewatch gag comedies. One Punch Man starts out as an anime with one joke — “Saitama can defeat anyone in one punch.” It develops further than that, establishing the world, other characters, and showing how a lot of the time, simply punching the problem won’t help.
The issue is that the first season only shows the hints of how complex the series actually is. The majority of people who liked it just wanted to see something new and exciting, and were blown away by great animation. Needless to say, it won’t be as exciting on a rewatch — and the second season, with its subpar animation, would be even more disappointing.