aww, this is so cute. A rather realistic portrayal of sisters. I really hope they don't really 'kill' the 'mean mayu' because i like to think the lil sis is just exaggerating Mayu 'meaniness'
Also it's quite funny to think about how lil sis didn't want to tell what she's doing all day because imagine if she did talk to Mayu that she's holding a funeral for her, its so morbidly funny.