She calls them "oji-chan", meaning uncle, usually middle-aged, but she's so young the 20-something trio probably seems older.
Oji-chan can look and sound like Ojii-chan, or grandpa.
I hope this helps. I've read all the manga and seen some subbed anime.
Ok, now that's out of the way, why does Kisa also call Torhu sissy?
posted over a year ago
In the Japanese anime and the manga, she calls her Onee-chan, meaning older sister. It can be used both for sisters and for older girls who are like sisters.