Bride Shadow made two mistakes. 
1: She questioned Masako's honor and in extension her pride
2: Trying to be mean to an adorable puppy like human
XD

And so Masako used Heroic resolve! And depending on how Bride reacts this can either end horribly or rather touching. But it is a risk she is willing to take, because she is a hot headed idiot.

Oh and Haruto may have just been hit with the deadliest rubber band of all time. XD