I'm Straight, But My Friend Gets Me Hard

Atsushi can't rise to the challenge with his girlfriend and starts panicking. Could it be that he's run into a medical condition already!? Looking for help on the internet, he finds an article recommending a certain kind of stimulation that's apparently very effective... Unfortunately, just as he's trying it out, his best friend comes back home and finds him in a compromising situation. To Atsushi's surprise, Tsukasa rushes to the rescue and helps him achieve what his girlfriend couldn't... But, Atsushi is straight, isn't he!? How is this going to change their friendship...?