Beer On the Train
I had a beer on the train coming home. It's something I do occasionally, but which is sort-of frowned upon here in Japan.
It's tricky, but basically you have to pick your train carefully. On the Shinkansen ( bullet train), drinking is encouraged...
On the Yamanote line which circles Tokyo, cracking open an Asahi is not really done...
Lines which go to the countryside (ie with destinations more than an hour from Tokyo) are often filled with commuters, so drinking is OK...
I told you it was complicated - I got frowned at a couple of times today even traveling on one of the 'commuter' trains.
More than 6 years in Japan and I still don't know the rules...