High School student Masamune Izumi lives a balanced life between his career as a novelist, and looking after his foster sister Sagiri who became a shut-in a year prior. When Masamune's books became popular on the charts, he is demanded to be seen in public along with his illustrator, an anonymous person who goes by the pen name "Eromanga". Later on, when Masamune watches Eromanga Sensei's live stream as she was illustrating and chatting with her fans, he discovers that Eromanga Sensei's real identity is none other than Sagiri.