Marking this as Hilarious in Hindsight, because as of UDoaLG, it's confirmed that saki WAS Miko's horse.
People were already making this connection way before this post, there are dozens of examples. It was also hardly surprising when half the cast are based on or inspired by historical or mythological figures, with Miko herself literally being Prince Shoutoku.
Look, just because my battle theme happens to be called "Prince Shoutoku's Pegasus" doesn't mean that I, Saki Kurokoma, used to be owned by Miko Toyosatomimi.Well no, I suppose it doesn't.Wasn't Miko the name of your owner when you were alive?Prince Shoutoku!!Cut it out Saki-chan.