A fantasy story for kids featuring a girl named Melmo, who can change her age as she wishes by eating special candies.

Melmo's mother dies in a traffic accident, leaving young Melmo and her younger brother Totoo. Anxious, Melmo's mother in heaven asks God to prepare some magical candies, and hands them to Melmo.
There are two kinds: Melmo can grow 10 years older to become any sort of adult she wishes by eating a blue candy. By eating a red one, she can become 10 years younger.

Using these miracle candies, Melmo disguises herself as a nurse, schoolteacher, policewoman, and overcomes troubles together with her brother, Totoo.

This volume also includes the edition of Bouken Ruby serialized in Shougaku Ichinensei (for first grade students) and Shougaku Ninensei (for second grade students).