We have been good friends for a long time. - One day, I bumped into my older sister on the school bus! - The crowded bus shakes violently and gives my sister a wall-thump! - As it is, he is pushed by other passengers and his face and body are in close contact! - An unexpected erection even though they are siblings! - Naturally, my sister found out about my erection, and it was bad...! - As I was panicking, my older sister seemed to be in heat as well, so...