I’m not sure about the form of narau (learn) in this dialogue. It sounds like Hazuki says “naratteruno”, but a Google.co.jp search turns up no matches of this form of this verb. I have little confidence in my hearing of this word.
The following is from Ojamajo Doremi ♯, episode 19. On the Taiwan box set release, it’s roughly 01:29:00 into the DVD. The scene is when Nanako is recounting to Aiko, Onpu, and Poppu the events when young Hazuki learned young Doremi lied to her about what happened to the class rabbit. Young Masaru explained the reason for young Doremi’s actions, and young Hazuki approaches young Doremi to apologize for her reaction.
- どれみちゃん、ピアノ 慣らってるの？
- どれみちゃん、ピアノ ならってるの？
- Doremi-chan, piano naratteruno?
- Doremi, are you learning (to play) the piano?
- うん、おかあさんに ちょとね。
- un, okaasan-ni chotte ne
- Yes, a little by my mother.
- わたしも ヴァイオリンを 慣らってるの。
- わたしも ヴァイオリンを ならってるの。
- watashi-mo violin-o naratteruno
- I’m also learning (to play) the violin.