The train lurches, and Ayumi stumbles back, her small frame swallowed by the sea of commuters. A hand snakes around her waist, pulling her into a hard body. She looks back, meeting M-kun's heated gaze. His hands roam, cupping her breasts through her uniform, pinching her nipples. She gasps, her panties growing damp. The train jolts again, and she feels him, hard and insistent, against her ass. His hand slips into her panties, finding her clit, rubbing in tight circles. She bites her lip to stifle her moans as he lifts her skirt, exposing her to the train, and enters her in one swift thrust. The train's motion masks their movements as they fuck, their bodies pressed tightly together, each thrust pushing them closer to the edge.