Artist's commentary
Kyogoku
Minamoto-no-Raikou apparently gifted thirty horses to guests when the new Nijyo-Kyogoku was completed by Fujiwara-no-Kaneie, Fujiwara-no-Michinaga's father.
In so doing, Raikou managed to establish an intimate relationship with the Clan of Fujiwara-Sekkan.
Kyogoku, the black horse adorned with bull horns.
A riding horse created using Raikou's magical energy as its power source.
Raikou likely chose his name in reference to those thirty horses.
To protect Chaldea's decency with his master, Kyogoku awaits her next order.
Even if his master's existence was only possible by her changing her own Spirit Origin...and even if it may be an illusion that lasts only for a single summer...