Attack on Titan is the big anime franchise that singlehandedly saved both the manga and the anime market in the West. When it premiered in 2013, the anime and manga worlds were looking a bit lackluster with old genres and tropes, and its high concept intensity captured the imaginations of fans worldwide. It is the anime answer to Game of Thrones.
It's not facetious to say that. There's a long list of parallels Attack on Titan has to Game of Thrones. Both are genre-busting fantasy epics that subverted decades of audience expectations for the genre. Both revitalized a genre that was starting to feel tired. Both are set in dystopian alternate histories where kingdoms are at war with a larger menacing threatening the end of Humanity. Both have unpredictable plotting that kept audiences on their toes and shocked them with unexpected deaths of fan-favorite characters who would normally be protected by plot armor in more conventional stories. Attack on Titan may have killed off more beloved characters than Game of Thrones. When the characters embarked on a campaign, nothing ever goes according to plan and the heroes usually get out by the skin of their teeth, with either no victory with one on the slimmest of margins, paid with major losses.
Attack on Titan has the killer high concept, though: a kingdom has to fight off giant naked zombies. Zombie dai kaiju! A melting of three genres: zombie, kaiju, and fantasy. It's a combination that could only come out of Japan. Now the manga has reached its climactic battle with only three chapters left before it ends once and for it. And the anime has entered its final season, adapting the start of the manga's final arc. The second half of the season will be later this year, adapting the rest of the anime.
Unlike Game of Thrones, Attack on Titan will have the ending of the manga from this April to adapt. The anime series has been a faithful adaptation of the manga, expertly condensing literally thousands of pages of plot into a concise shorter season. And even like Game of Thrones' final season, it features a heroic character's heel-turn that turns the entire series on its head. Like Daenerys Targaryen's degeneration into a world-threatening despot, the hero of the story has turned into the series' new, true, and ultimate Big Bad. It's absolutely logical and once again, no one is safe. Beloved characters that have been there since the beginning are getting killed off.
Once the series is over, it'll be the end of an era. That apocalyptic intensity and the audience's anticipation will be done, and the search for the Next Big Story will begin again.