@Gulcasa
it's not 2013. It's just typical sliding timeline very common for manga, animations etc. Take Simpsons for example. In Watatmote College arc there was a booklet called "2018 college guide" or something like this, so Watatmote happens not in specific years, but "now"
At least Watamote is moving forward, there are a lot of works where characters stay the same age for years and decades, like in above-mentioned Simpsons.