Majo Ume is a resident of Witch Frog Town in the Witch World.
During a powerful storm in the Witch World, Majo Ume and her fellow Witch Frogs were blown through a doorway that connects the Witch World to the Human World. Landing in Onpu Segawa's office, they proceeded to have a wild party, drinking alcohol and dancing. At some point in the night, Majo Ume wandered outside the office building and found herself at Mahou-Dou. Still heavily intoxicated, she proceeded to doodle a mustache on Majo Rika's face in her sleep, then afterwords fell asleep herself in the closet.
The next morning the Ojamajos brought the remaining witch frogs that were in Onpu's office back to Mahou-Dou so they could reunite with Majo Ume. The witch frogs then refused to return to the Witch World until they got in some sightseeing of the Human World with the Ojamajos as their escorts.
The last activity for the sightseeing day, requested by Majo Ume, was to visit an amusement park. She regrets that she had turned into a witch frog before ever getting to visit one, since it's something she's always wanted to do. The girls then perform a Magical Stage, which creates a miniature wind-up amusement park. The witch frogs cast a bit of magic to shrink themselves down and hop aboard the rides while the girls turn the lever.