Chumbud here. I've listened to Suisei, Azki, Lamy, Rikka and Towa all of them are amazing singers but none of them can control their voice like Gura. She has a big problem with her breath control and Suisei is better than Gura technique wise.
https://www.youtube.com/watch?v=ei4Zokk5kGs&t=255s 