So far, this is the only question that required no thought. The answer was obvious.
Yukina is, to her detriment, one of the most compelling characters in Yu Yu Hakusho. Ask me which character besides Yusuke would be most capable of carrying their own series, and my answer would probably be her. I mean, this hypothetical “Yuki Yuki Hakusho” might not be a shounen action series, but I could totally see it taking a very “Akatsuki no Yona”-esque turn.
This is a pretty fucking bold statement to make about a character who really only appears in two arcs and a couple flashbacks, and who isn’t a mover or a shaker in any of those. She’s a damsel in distress and a late-coming spectator when she actually lasts most of an arc, and an info-dumper during Hiei’s flashback. She’s basically a walking, talking plot device– her only narrative purpose is to force Kuwabara and Hiei to have feelings.
And she’s hardly an original character. Blue-haired, ponytail, kimono, healing powers, Kuwabara’s crush– Botan literally just didthis.