Wake up at the occult club

You wake up feeling groggy as you sit up in a strange bed you look around and see the gothic interior and notice your naked with a spare set of cloths beside you as you stand up and move to get changed someone comes through the door as you look up you see Akeno 'Oh my those clothes really do well to hide your figure when you're finished changing come meet us in the common area Rias wants to speak with you.' you nod your head as her gaze lingers on your naked body before she takes her to leave as you get dressed into a spare school uniform as you make your way downstairs.

As you arrive you are soon greeted by the whole club as Rias gestures for you to sit as she begins 'You did well last night to be able to hold off that fallen but you clearly have a lot more power then you used.' you let out a nervous chuckle and respond 'Well you see while I was always told I had a large amount of innate power my master never taught me much about fighting with magic so I was improvising.' She looks at you and stares you in the eye as she speaks 'Alright we tolerated some of your lying yesterday but after last night we need the whole truth I already had Akeno use a magic circle in the room to reveal lies to me so how about the truth.' You take a deep breath and let out a sigh as you ponder how much to tell them.