1boy, 2girls, age_difference, blush, book, breasts, brother_and_sister, comic, eyebrows_hidden_by_hair, greyscale, hair_over_one_eye, height_difference, holding, holding_book, hoshiinasake, indoors, large_breasts, long_hair, looking_at_viewer, mature_female, monochrome, multiple_girls, open_mouth, original, school_uniform, serafuku, short_hair, siblings, sweater