[There's only a brief moment of surprise both when the backs of his knees hit the bed, and then the way he tumbles back upon the bed. Instead it has him holding onto Soushi even more.
However the kiss does momentarily break when Kazuki scoots further up the bed. He tugs Soushi up closer immediately after until they're seated facing each other, Kazuki's legs wrapped around his waist. He meets his gaze only for a moment, both hands moving to cup either side of Soushi's face before continuing their kiss.]