OK, listening to this, it's interesting to hear them again in a fully live context from early on, in a faster-paced song.
2:11 The vocals only really started for me at this time stamp in the video when Keiko came in with her solo section mirroring Hikaru in the first verse. Her smooth, warm voice, and consistent pitch, settled the song.
Hikaru's pitch was unsteady from the get-go and she was clearly tense in her throat. You can see the veins popping. Thankfully, her technique would get a bit more refined as the group continued in the years to come. The seeds of her technique issues were already visible though. Her pitch was actually affecting the rest of group in harmony sections in the group.
There was a tendency to get over-excited especially for Hikaru, for whom the excitement worsened her vocal performance. She wasn't as focused on nailing the pitches as expressing herself physically. She seemed to settle a bit after Keiko's solo, maybe she was influenced a bit at that point.
3:16 Wakana was also a stabilizing factor with her calm singing. Hikaru was just yelling all over the place, to be honest. When she sang more controlled she was more on pitch. I would have preferred to just hear Keiko and Wakana sing the song.
