初めて出来た経験豊富な年上の彼女。手ほどきを受けながらセックスすることに。
だけど行為が始まると、余裕のあった先輩の様子がおかしくなって…。

My first girlfriend, an experienced older woman. I had sec with her while being taught how to.
However, when we began, the composed senpai started behaving strangely...