She needs a power up, the Ayakashi corrupt form under control will a great plus, but ok, now we have drama =(But @kwendy is right, that is weird for her to attack this guy.
He is like the last boss, why did she just go for that?
If she just follows him silently then it's very easy to accept, but she openly attacks him.
Why?
This is just for pushing the plot, nothing more.
Just what in the fuck this guy wants? He wants Yato to be killer, who keeps killing people for fun.