I had my first experience of chikan in Tokyo. Did I do the right thing?

I was on a night out with my friends in Shinjuku, and because I’m learning Japanese I like talking to random people on the street when I can.

I ended up having a random man come up to me when I was very drunk talking to me in Japanese and I was so drunk and trying to understand what he was saying I didn’t even realise till about 5 seconds later that he was attempting to grope me. As soon as I realised I completely had a physical reaction and punched him pretty hard. He kinda freaked out and I ran off.

I know he was the one in the wrong but I’m worried I did something wrong too. Was my reaction ok?

edit: I feel the need to clarify that I was not alone, I was with friends they were just nearby and I was at a slightly different part of the street. I went straight back to them when this happened and the guy had disappeared by the time I got to them.