Yongae Asano...she's been on a few of Ayu's tours now. I think she was in CDL2013-14, POM 2018, CDL-2018-19, Power of A^3 and CDL 2019-2020 so far. I may have missed a few but those are from the top of my head... I think she also has a youtube channel as well, but there's not much on there
https://www.youtube.com/user/yongae114