[China] Imouto wa Doujin Shoujo Cosplay Kei Ch.1-7 [biribiri]

Bookish doujin girl Kozue gets the confession she never expected from her own brother—'I love you regardless of whether you're my sister or not'—and answers with a dare: prove it. What follows is a cosplay-fueled sibling affair that escalates from the school clubroom to the bedroom, the teary, bespectacled twintailed girl trading her uniform for maid outfits and roleplay characters as her onii-chan claims her first time, while other bold girls like the sharp-tongued Saginomiya Haruka line up to test his devotion too. By the epilogue the pair have flunked their supplementary exams after a week-long marathon, squabbling like an old married couple while classmates groan at the newlyweds' antics.