Aho-Girl: A Clueless Girl Vol. 8 (manga)

Little Ruri is struggling with her studies, but her elder brother Akkun, ever mindful of a good education’s value, is determined to tutor her through her academic slump. There’s no motivation like direct experience, and both Ruri and Akkun know perfectly well what the endgame of foolishness is. And yet—is being Yoshiko so bad? She always seems to be having so much fun. The real lesson may very well be that while scissors beats paper and rock beats scissors, stupidity never loses.