This series was picked up by Studio Shaft mainly to cheer their staff up after making Puella Magi Madoka Magica.
Just like Studio Gainax with FLCL after Neon Genesis Evangelion.
Erio has an extreme form of Asperger's Syndrome or maybe some autism.
Just my forty cents...
Ryuuko has ADHD.
Meme also has ADHD.
I hear that crap's going around, perhaps even worse than Asperger's.