Ojamajo Adventure: Naisho no Mahou

Majorhythm is a young witch that lives in the Witch World. She's madly clumsy, and her workmates are always mean to her because she can't do her job properly, and they say bad thing about her behind her back. One day, the Queen gives her an errand; she has to deliver a letter to Majorika. She goes to the Human World, but she quickly gets lost. Feeling defeated, she sits down on a swing in a park, where she meets and befriends Doremi. Thanks to Doremi, she manages to get to the MAHO-Do. There, she meets the rest of the girls, and after waiting outside the store for a while because Doremi had forgotten the keys, they end up reading the letter, since it was actually adressed to "Everyone at the MAHO-Do". The card reveals that the Queen would like the girls to let Majorythym stay with them for 8 days, so that they can teach her how to do her job properly.

[From Ojamajo Doremi Wiki]