Totoo Watari is Melmo's younger brother and the elder sibling between her and their infant brother Touch. After their mother's death in a car accident, he lives with Melmo and Touch.

Totoo displays a smart, observant nature. He once prepared multiple bottles of fake magical candies to confuse a suspicious woman seeking them, showing resourcefulness. He also exhibits mischief, having taken Melmo's candy bottle and teasing her by refusing to return it. This act led directly to his accidental transformation: after learning the candies could turn him into an animal, he consumed both a blue and red candy simultaneously while envisioning a frog. This trapped him permanently in frog form.

As a frog, he retains his distinctive red coat but is too small to physically consume the candies needed to revert. He remains in this state for nearly half the series while Melmo works persistently to find a solution, ultimately succeeding in restoring his human form.