His mind had taken a backseat to his body this time. Without his calculating thoughts, his nature as Kira was emerging. His body had never felt this type of sensation before and it knew it wanted more. Somewhere deep inside, part of Light's reason may be calling out to him to control himself. However he was hearing none of it. Feeling her muscles contract as she began to ride, he began to move his finger in and out in timing with his cock, letting the digit burrow deeper. His legs began to tense up as he twitched hard in her cunt, nearing his release. Not to say his body moved entirely on instinct. Even as Kira, he had booksmarts and would use them.
He remembered a class on anatomy and began searching with his finger, knowing that what he seeked was somewhere around there. Pressing up, he began to push in all directions separately, as if attempting to loosen her. However, his true aim was for her prostate. Finally reaching the point he managed it to be, he pressed down on it. The reason being, that the muscle itself was one of the most sensitive that the body had and would cause all her other muscles to clench up as well that were around it. He moaned as he felt her body tightening around his invading extremities. Pounding harder against her, almost as if to drive her in and through the wall, he continued on licking at her nipples as he did so.