Izumi is... well was.. or maybe is a failing light novel writer. His novels have gained fame thanks to the great talent of the artist who goes by the pen name Eromanga-sensei. Now in traditional anime fashion there needs to be a twist. Turns out that one day Izumi learns the secret that his own shut-in sister is in fact Eromanga-sensei. Now comes the awkward tail of a step brother and step sister team.. or something like that.