Miyabi (雅) is one of the traditional Japanese aesthetic ideals, though not as prevalent as Iki or Wabi-sabi. In modern Japanese, the word is usually translated as “elegance,” “refinement,” or “courtliness”.
But from my point of view, she doesn’t posses any elegancy at all.
She known as one of Berryz main vocal after Risako. She always try to dominate the groups in every chance, bossing around, and even tries bully the other member. She don’t give any mercy to the younger member. Maybe she looks nice but, if we look closer, it’s like just she said “Come and have fun with me, but follow my orders and don’t even try to reject or you’ll suffer”. For the older member, only one person that she recognize as worthy to respect, Saki-chan. Or maybe too respectful to her as we can see Miya always want to side-by-side with captain anytime.
She also has a leadership sign with her attitude like that. Before Momo was choosen as Buono! leader, many people believe that Miya was the leader of the group since she always bossing around in Buono. And of course, i think Miya were recognized this opportunity too. She leads Buono! movement until Kiss Kiss Kiss single. And in this period, Miya’s performance in many event and concert was in maximum. In Berryz vs C-ute Battle Concert, she is one of the most energetic singer and dancer till the end.
Thanks to unconfirmed scandal issue with one of JE member last year. Her popularity sky dived to the worst. Her solo lines in the next Berryz and Buono! releases were reduced dramatically. The results, now she didn’t perform seriously in many live event except for the song she had enough fair lines and she think she can dominate the whole performance. Her worst performances were with “co.no.michi” song. You can judge by yourself that everytime she performed this song she wouldn’t take it seriously.
If you watch again Hybrid Punch concert, you’ll see the difference her performance quality for each song. For a sample, in the climax for this concert, Kiss Kiss Kiss, Momo and Airi were struggle to keep their voice at their best because they’re already too tired. But, Miya is different. Since this is the only Buono! single that she most dominated (if performed together), somehow we can see her true ability for keeping her vocal stability even in exhausted condition just like in the past when she owned the Special Generation in every performance.
My conclusion is, the reason behind her behavior is PRIDE. Her pride feeling is the highest amongst any ex-Hello Pro Kids members. And this pride sometimes lead her to become very cold to the others because she will feel higher than the rest.