When was That Time I Got Reincarnated as a Slime first released?

If you’ve ever dived into the world of isekai stories, chances are you’ve stumbled across That Time I Got Reincarnated as a Slime. Even if you haven’t read the light novel or manga, you might have at least seen the anime floating around in recommendation lists or heard people talking about Rimuru Tempest, the adorable slime that somehow became one of the most beloved protagonists in the genre. But a lot of people who are new to the series end up asking the same question: When exactly did it all begin? When was That Time I Got Reincarnated as a Slime first released?

The funny thing is, the answer depends a little on which version you’re talking about. This series has been through multiple stages, first as a web novel, then a light novel, then a manga, and later on, a hit anime adaptation. Each “release” drew in a different group of fans, and that’s part of the reason the series has become such a massive phenomenon.

Let’s start from the very beginning. Tensei Shitara Slime Datta Ken (the Japanese title) was originally published as a web novel back in 2013 on the site Shōsetsuka ni Narō, which is basically a huge online platform where authors post their stories. A lot of popular isekai titles were born there, and Slime was one of its biggest success stories. Imagine browsing random web fiction and stumbling upon a story about a 37-year-old man reincarnated as a slime. It probably felt like a joke at first, but clearly it had something special, because it quickly gained traction with readers.

Then, in 2014, the series officially got picked up as a light novel by Micro Magazine. This is where you can say the “real” release happened for a lot of fans. The light novel, written by Fuse and illustrated by Mitz Vah, polished up the story and gave it professional artwork. If you ask long-time fans when That Time I Got Reincarnated as a Slime first released, many of them will point to 2014 as the moment it truly began. Reviews from back then praised the unique twist on the isekai formula. While other protagonists were overpowered humans or chosen heroes, Rimuru started out as a slime, and yet somehow became one of the strongest and most charming characters out there.

But the series didn’t stop there. In 2015, the manga adaptation by Taiki Kawakami began serialization in Monthly Shōnen Sirius. For a lot of people who prefer manga over prose, this was their first real introduction to Rimuru. And the manga really helped bring the story to life in a more visual way, letting fans see Rimuru’s transformations, allies, and growing kingdom in full detail. If you want to explore more about the manga specifically, you can always check out tenseishitaraslimedattaken.com, which gathers updates and details about the series.

Fast forward a bit, and we get to what arguably catapulted Slime into mainstream global popularity: the anime. The first season of the anime aired in Japan in October 2018, produced by 8bit, and it was an instant hit. That was the first time a lot of international viewers discovered Rimuru’s journey, and suddenly, the slime who started as a web novel character was now a household name in anime fandom. Reviews were glowing, people loved the balance of humor, action, and surprisingly deep worldbuilding. And of course, Rimuru’s design as a slime was way cuter than anyone expected.

So, depending on who you ask, That Time I Got Reincarnated as a Slime was “first released” in 2013 (the web novel), 2014 (the light novel), 2015 (the manga), or 2018 (the anime). And honestly, all of those answers are right. It’s like asking when a band really started: was it when they posted their first song online, when they signed a label, or when they had their first big concert? Each stage matters, and each brought in more fans.

What’s interesting is how the timing worked out. By the time the anime dropped, the story already had years of material built up. That meant the anime had a solid foundation to adapt from, which helped it avoid the pitfalls of some other rushed isekai adaptations. Reviews often point out that the pacing felt just right, and that’s largely because the source material had already been developed and well-loved by a core fanbase.

When you look back at the release timeline, you can also see how Slime grew with its audience. In 2013, it was this quirky little online novel. By 2014, it had become a respected light novel series. By 2015, manga fans could get into it too. And then by 2018, the anime had it a global name. Now, it’s not just one of the most popular isekai, but one of the most popular fantasy series of the last decade. It’s wild to think all of that started with a middle-aged man getting stabbed and waking up as a slime.

Another thing worth pointing out is how the release of each version influenced the fandom. Fans who started with the web novel tend to be the most hardcore; they were there when Rimuru was still a niche curiosity. Fans who joined with the light novel often rave about the illustrations and expanded story details. Manga readers talk about how fun it is to actually “see” the characters and battles play out. And anime fans, of course, are the loudest online, filling forums with reactions, memes, and theories after every episode. Each wave of release built on the last, making the series bigger and bigger.

So, if you’re answering the question most simply, That Time I Got Reincarnated as a Slime was first released as a web novel in 2013. But if you’re talking about when it “really” entered the larger public eye, then you’re probably looking at the 2014 light novel release or the 2018 anime adaptation. And honestly, that flexibility is part of the charm. It’s a series that grew organically, layer by layer, from web fiction to a global franchise.

And here we are today, years later, still talking about it, still waiting eagerly for new chapters, seasons, and spin-offs. Whether you first picked it up in 2013 or discovered it on Crunchyroll in 2018, the magic of That Time I Got Reincarnated as a Slime lies in how it makes even the weirdest premise feel epic and heartfelt.

So, the next time someone asks you, “When was That Time I Got Reincarnated as a Slime first released?” you can smile and say: “Well, it depends, do you mean the web novel, the light novel, the manga, or the anime?” And then, of course, you’ll probably end up recommending they check it out themselves, because the journey of Rimuru Tempest is just too good to miss.