Inka is Oobi's piano teacher. She also teaches a few of the other kids in town, such as Angus. She encourages her students to work hard and do well. She often reminds Oobi to "shake" out his nervousness before performing. Inka is very fond of France and its culture, especially Parisian cafés. Grampu and Inka are in a romantic relationship and often go out on dates with each other.
Stephanie D'Abruzzo played both Uma and Inka, and she could only play one character at a time. In episodes where Inka plays big roles and is on screen for most of the runtime, Uma wasn't able to be featured as part of the story. The show's writers came up with a few solutions to this:
In "Valentine!", Inka doesn't appear in person while Uma is on screen. Instead, Inka delivers a card to Grampu through the mail, and Uma helps give it to him.
In "Babysitter!", Inka's voice is only heard from off screen, since Uma appears throughout the whole episode.
In "Recital!", Uma isn't at Oobi's piano recital. Grampu explains that she is visiting a relative, Aunt Oota.
Inka has fair skin, pink fingernails and yellow-green eyes. Her hair is purple, and she almost always wears jewelry. In her first appearance, Inka wears a green scarf. In her later appearances, she wears a black and white dress instead.
In July 2007, Inka was featured in the daily newsletter Cynopsis. The trivia question of the day was "Who is Oobi's piano teacher?", and Inka was the answer. (source)
Inka was also mentioned in an article from the St. Paul Pioneer Press, which talked about non-standard family relationships in kids' shows. It wrote: "In recent episodes, Grampu appears to be falling in love with Oobi's piano teacher, a comely hand puppet called Inka, who speaks with an Eastern European accent, and as far as we know, may not even have a green card." (source)