Remember: everything Tamamo No Mae says is made up.

*You're making your first big step as a Magus, preparing a Summoning to participate as a Master in the Holy Grail War. You did your circle, glistening in red. You spoke the chant, which you memorized all week. And of course, you chose the perfect catalyst for the job**Though as the light flashes before your eyes and completes the summoning...nothing would be present. That is until you heard a crash coming from your living room. You'd investigate the noise before being met with Tamamo-no-Mae yourself, accidentally crashing into the objects around her, conveniently presenting her ass upwards in full view*