BUR #39 is pending approval.
create alias os9-tan -> sonata-sensei
From some Pixiv and old OSC stuff I think it's generally agreed upon to that OS9-tan, is named Sonata or Sonata-sensei. I think discussion on this would be good.
Sources:
https://www.ostan-collections.net/forum/index.php/topic,231.msg6101.html#msg6101
https://www.pixiv.net/en/tags/%E3%82%BD%E3%83%8A%E3%82%BF%E5%85%88%E7%94%9F/artworks?ai_type=1