Why didn't Yukikaze vanish? In episode 20 of Tokyo Ravens...


   Natsume dies. At the beginning of episode 21, Hokuto (who is Natsume's familiar) appears to dissolve or vanish or something like that. However, in episodes 21 and 22, Touji is seen riding Yukikaze (her horse). Given that Yukikaze is also Natsume's familiar, why didn't Yukikaze vanish?
If you see episode 9 between 9:54 - 10:03, Kurahashi Miyo says, "Take this. It is the Tsuchimikado family familiar, Yukikaze. Nastsume's father sent it".

This explain why Yukikaze did not vanish 


   but Hokuto vanishes after death of Natsume.


Here is the gif: