I quickly noticed while doing this challenge that the "episodic" term can be more subjective than one would imagine. There's a couple of series like Mushishi that leave no trace of doubt about the episodic nature, but there's also a lot of them that are not. Because of this, I'm turning this with a couple of notes, especially since probably the one in charge of checking this challenge will not have seen some of the entries:
Gintama entries: Gintama is a bit like Detective Conan in this regard. Just like Conan, there is a big story behind which has a slow but steady progress, and there's a couple of episodes here and there that are the "main story" arcs, just like Conan has the Black Organization episodes. But the vast majority of Gintama can be watched in any order... and you could even argue that you can watch those main story episodes in disorder. Even more, I've seen fans in the forum recommending to start with the later Gintama seasons because of the famous "slow start" of the first season. Episodes are mostly one or two episodes stories that have nothing in common among them. Also, about this big story behind... you could actually argue that all three anime from the badges have that, and it's even more present in those as they're shorter (Trigun, Champloo and Bebop).
Hidamari Sketch: Cute Girls Doing Cute Things. While times does go by in the series. There's not a single trace of story really... even a single episode can have many short stories with no relation at all.
Nichijou: Same as Hidamari.
Saa Ikou! Tamagotchi: Short series meant for kids that doesn't really tell a story, just show different situations in each short episode.
Bananya: Same as Tamagotchi.
Popee the Performer: Dementia shorts really that show different "circus" shows in each episode. Characters don't even talk, and there's definitely no plot in the series.
GA: Geijutsuka Art Design Class: Almost literally, same as Hidamari (both have cute girls in an art school)
Hakaba Kitarou: The first episode pretty much tells the story about how Kitarou was born and from where does his "dad" come. But other than that, the series present each episode with a different monster and a different "case" to solve. Sometimes there's a small line connecting episodes, but there's no real actual progress and definitely no conclusion or something like that. Each episode is a different situation.
Petshop of Horrors: This is about a guy who owns a creepy pet shop where he sells "special" pets. Each episode is a different costumer. There's no story progress.
I probably wouldn't even turn this in until hard if it wasn't because it's a bit more difficult to judge.
Added
AYOSHINADec 16, 2016 4:49 PM
People need societies, but they don't necessarily need nations. - Yang Wen-li