This episode starts with something unusual: Yato actually teaches something useful to Yukine. In his first try, Yukine manages to create a barrier between himself and an ayakashi.
Next, Hiyori decides that Yato is incapable of taking care of Yukine. Therefore she decides that Yukine should stay with her. What she didn’t know, is the reason why Yato usually choose to sleep in a random shrine: because shrine provides protection against ayakashi so they can sleep safely. Hiyori’s home is a lot more comfortable, but it doesn’t provide protection. So Yato stays near her house to protect him.
At night, Yukine is afraid of dark room and Hiyori invites Yukine to sleep with her. I guess Hiyori doesn’t see Yukine as a man at all. Perhaps she sees him as a younger brother.
Our victim today is a spirit of a young girl who died of a car accident. She doesn’t realize that she’s dead. Instead she’s just sitting near her place of death, waiting for her mom to pick her up and wondering why other people ignores her. Yukine can see the little girl.
In the end, the little girl is consumed by evil ayakashi and Yato has to slay the ayakashi to “free” her. Yukine learns his lesson, the hard way.