YOU SAID:

I used to play the piano when I was younger, with my sister

INTO JAPANESE

私は幼い頃、妹と一緒にピアノを弾いていました

BACK INTO ENGLISH

When I was little, I used to play the piano with my sister.

INTO JAPANESE

小さい頃、私は妹と一緒にピアノを弾いていました。

BACK INTO ENGLISH

When I was little, I used to play the piano with my sister.