Yukina was one of my favorite supporting characters.
I felt so bad for her because she was imprisoned because she can make very valuable jewels with her tears.
Kuwabara falls in love with her at first sight, ironically not knowing that she is Hiei’s secret sister.
After being freed, she shows up to lend support for the characters. Mostly as a healer.
I thought it was funny that she didn’t realize Kuwabara was quite in love with her at first.
But I think she learned that later on.
During the last saga, she becomes an attendant to Genkai.
I think the anime doesn’t suggest she knows that Hiei is her brother. But I think in the manga it suggests that she’s figured it out.