I want to share an experience and some advice.
The other day during rush hour at Nagoya Station, it was incredibly crowded because of GW. I was the last person in line to board the train. As I entered, I had to adjust my position to avoid the closing doors and to maintain distance from the girl in front of me. In the process, I accidentally bumped into the arm of a Chinese guy who was hugging his girlfriend.
He started pushing me and continued to do so until the next station, staring at me through the reflection in the window. To avoid a fight, I decided to get off at the next stop. As I was exiting, he tapped me on the arm. Being surprised, I instinctively reacted with a QUICK JAB to his lower ribs (unguarded due to hugging position). He looked uncomfortable and didn't say anything; we just stared at each other before I left. Maybe he is a tourist or can’t speak proper Nihongo.
My Advice: I know I was wrong to react that way—it was a split-second 'auto-reaction' because I was startled. If he had reported me, I would have stayed to explain my side, but the reality is that in Japan, walking away is winning. Even when you feel the need to defend your dignity, it’s a tough pill to swallow, but avoiding the escalation is the only way to stay safe. The fact that I got out of there without the police being involved is a huge relief, and I hope others can learn from my experience.