My Little Sister is My Diehard Fan

When they were children, Shirabe Yamada encouraged her brother Minoru to become a mangaka, but years later, and now that she's a high-school-age streamer, she can barely stand him. Now a university student and amateur mangaka, Minoru does his best to keep his craft a secret from her, but on the day his manga is cancelled by the publisher, Shirabe accidentally discovers his studio at his room and that he's the mangaka 'Aoi Ringo'.

Shirabe then confesses to him: she's Aoi-sensei's diehard fan!