Both the "Attack on Titan" anime and the manga series deal with humanity's failure to look out for another — as well as the political fallout from something as devastating as gigantic monsters rampaging through the world. Basically, the Titans are scary, but the human race can be scarier at times. It's not a subtle theme, but it doesn't need to be. When asked about what inspired the series, manga creator Hajime Isayama told Nihon TV in 2013 (via Anime News Network) that he came up with the idea for the Titans after meeting a drunk person at an internet cafe.
According to the publication, Isayama was inspired "by the lack of the ability to communicate even though the person was of the same species." He also thought that out of every creature in the animal kingdom, humans had become not only the most ubiquitous but also the scariest species. Well, the thought of giant drunk people rampaging through the streets is definitely terrifying. Still, it'd be interesting to see where Isayama got the inspiration for the Nine Titans since they all feel pretty unique next to the others.
