Miyagawa Atsushi is an 11-year-old boy who is 180 centimeters tall. Since he has a grown-up looking build but acts his age, he has always been running into troubles. On the other hand, his 17-year-old elder sister Atsumi is only 137 centimeters tall. Even though she has a childish looking build, Atsumi takes good care of Atsushi.

[Source: MyAnimeList]

Unaired episodes bundled with the special edition of volume 4 of the original manga.

Unaired episode 13 included on the Blu-ray/DVD volume of the Recorder to Randoseru Mi☆ series.