Hitomi smiled to Trina..her innocent little niece wasn't so innocent anymore, now was she? Hitomi kissed Trina's lips, tasting the girls fake 'cum' on her lips after she had sucked it off her finger, and smiled softly to her Niece. "ooh..I have another way to keep her silent.." Hitomi said with a smile, smirking as she waved her wand at her bra, making it come over to them. With a tap, the bra changed into a rather cute collar. "Hmm..With this..if she tries to tell anyone what happened here, she'll be silenced immediatly..." Hitomi said with a smile, slipping the collar easily around Rika's neck and placing a curse on it to make it irremovable until Hitomi herself wanted it to come off. "And...with just a little wand flick.." Hitomi smiled evily, flicking her wand towards the collar....a sudden surge of pleasure lit up Rika's body. "We can make her experience the thrills she just had any time we want." Hitomi said, grinning to Trina as she kissed the girl's lips, using her ability to make her own cock go away, leaving her crotch smooth and hairless. She looked at Rika, smiling. "...There are three spells on that collar, girl....One will make you silent if you ever try to talk about what has happened..or will happen to you..." Hitomi smiled, sliding a finger into Rika's folds. "One that will make you nearly orgasm each time a special word is spoken..." Hitomi smiled, pulling out her finger and suckling on it softly. "..and the last spell...with one word, either of us will be able to call to our location..at any time we want.." Hitomi said, looking positively evil as she kissed Trina's lips again, and whispered the special words for the collar into her niece's ear. "You're going to be our little pet for the rest of your term here at Hogwarts, Rika...but don't worry..we'll make sure you enjoy every minute of it.."