Recorder and Randsell OAD. Atsushi Miyagawa, an 11-year-old boy in the fifth grade of elementary school, somehow already has the appearance of an adult, standing at 180cm tall! This appearance causes all sorts of troubles in his daily life. At the same time, he has a 17-year-old sister, Atsumi Miyagawa, currently in her second year of high school. But this terrifying family has only given her a height of 137cm, with a loli physique! Despite this, the older sister still does her best to take care of her younger brother.