Matthias braced himself against the door, fighting to hold back the Rider for just a few more seconds so that...well, people tended to freak when they saw him transform into a black leather wearing guy with a skull on fire for a head.  "Yuriko...go check around back, will you?  I don't know if there's more than one entrance to the house."  She might not be able to do anything against the demon, or whatever it was, but hopefully his attack would be quick and brutal enough that he wouldn't have to worry about it.  As soon as she was gone, he would let go, stop trying to hold back the change.