The timing of this article feels like it was written in response to Singapore banning a Swedish black metal band from performing at the very last minute.
I fly halfway across Japan about every two years for metal concerts in Osaka. Big-name extreme metal acts usually only visit Tokyo & Osaka. About 3-4 years ago Watain was headlining a show. I would have been PISSED, having bought a plane ticket and a hotel, only to find the headline act was cancelled due to some nonsense. \m/>_<\m/
Usually I just wait for something to pop up on my feed on Facebook, probably based on some of the bands I follow. Here's Osaka's most common metal venue: