Another month sees another Metro Manners installment. This time, I think they were hinting at last years overly raucous Yamanote line [山手線] - actually on JR and not on the TOkyo Metro - party which, until last year, used to take place yearly (Halloween time) on the said line. Basically, someone would organise a particular carriage and train, and people would turn up in costume with alcohol. The party carriage would do its loop of Tokyo and partying would be had.
This was all well and good until last year, where things got a little silly and (mostly drunk foreigners) over-enthusiastic/socially inept people managed to harrass innocent commuters and break stuff in the carriage. Anyway, the actions of some idiots managed to get JR very upset, and call in extra security to ward off any idea of a party on the Yamanote line this year. And it would seem that Tokyo Metro would like to point people in a similar direction.