Masamune writes light novels for a living, but his professional life crumbles when his only illustrator vanishes without explanation. The artist behind "Ero Manga Sensei," a pen name for someone cranking out provocative cover art, goes radio silent right when he needs them most. His personal life isn't better: his younger sister Sagiri has barricaded herself in her bedroom for a year straight, refusing to leave for anything except to stomp demands for food down the stairs. When Masamune finally tracks down his mystery illustrator, the revelation hits like a truck. Sagiri is Ero Manga Sensei. His shut-in sister is the perverted artist he's been working with all along, and she's actually brilliant at what she does. Now Masamune has to convince her that the world outside her room isn't so terrible, all while keeping her artistic career alive and navigating the awkwardness of having a little sister who draws exactly what he doesn't want her drawing. A comedy about sibling chaos, creative partnership, and the messy reality of pursuing your dreams alongside the people closest to you.