From Hoshikuzuu Scans:

There is a 25-year old, hard-working salaryman named Satou Hajime. After pulling an all-nighter and taking the early train home, he overhears someone watching a porn video on the train, giving him a stiffy. Thinking that it was some perverted virgin listening to it, he’s surprised to find a hottie. To apologize for the trouble he’s caused, the hottie "takes care" of him. Will Mr. Virgin lose his virginity!?