I mean, this will sound kind of terrible, but you can tell that Wakana and Hikaru push themselves to hit their notes. You can see it in their faces. Keiko on the other hand generally looks relaxed during live performances and rarely needs to push her voice to reach above or below her natural range. Hikaru often goes a bit over her natural range or below, i.e. magia. Wakana is also almost always at the upper point of her vocal range as well.
It may be hard to tell, but her voice has been slowly recovering over the past few lives. 2014 was a bad year for both her and Wakana, and 2015 even more so for Hikaru. In the 2016 arena live, she sounds much better. For this song, especially.
