Hitomi smiled to Trina and nodded her head at her suggestion, moving her wand over Rika's body so that it was lifted up into the air, and turned around, placing her on her knees infront of Trina, Trina's large cock perfectly level with Rika's mouth. "Mm..." Hitomi smiled, whispering the word that activated the collar again, and when Rika opened her mouth to moan, Hitomi quickly and gently grabbed Trina's ass, pushing her hips forward so that her young niece's cock would cut off Rika's moan by stuffing her mouth full. She bent down next to Rika's ear, and smiled. "Mm...Give my little niece oral, and we'll let you go for the day, Rika..." Hitomi said, the look in her eyes and her smile indicating she wasn't lying. "Make her cum and we'll let you go for the day..I promise....and if you swallow her cum..maybe I'll mark your transfiguration grade up a little bit.." Hitomi offered, smiling to Rika as she stood up again. She took Trina's hand, and placed Trina's hand on her own throbbing cock, smiling to the girl. "Mm...Stroke me off while she sucks on you, Trina..." Hitomi said to her niece, smiling as she pulled the girl into a kiss, her hand falling on the back of Rika's head and forcing her to start bobbing on Trina's cock to get her going.